Cousin marriage
Encyclopedia
Cousin marriage is marriage between two cousin
Cousin
In kinship terminology, a cousin is a relative with whom one shares one or more common ancestors. The term is rarely used when referring to a relative in one's immediate family where there is a more specific term . The term "blood relative" can be used synonymously and establishes the existence of...

s. In various jurisdiction
Jurisdiction
Jurisdiction is the practical authority granted to a formally constituted legal body or to a political leader to deal with and make pronouncements on legal matters and, by implication, to administer justice within a defined area of responsibility...

s and culture
Culture
Culture is a term that has many different inter-related meanings. For example, in 1952, Alfred Kroeber and Clyde Kluckhohn compiled a list of 164 definitions of "culture" in Culture: A Critical Review of Concepts and Definitions...

s, such marriages range from being considered ideal and actively encouraged, to being uncommon but still legal, to being seen as incest
Incest
Incest is sexual intercourse between close relatives that is usually illegal in the jurisdiction where it takes place and/or is conventionally considered a taboo. The term may apply to sexual activities between: individuals of close "blood relationship"; members of the same household; step...

 and legally prohibited
Prohibited degree of kinship
In law, a prohibited degree of kinship refers to a degree of consanguinity between persons that results in certain actions between them becoming illegal. Two major examples of prohibited degrees are found in incest and nepotism. Incest is a taboo across all cultures worldwide, but which specific...

.

Such marriages are often highly stigmatized today in the West
Western world
The Western world, also known as the West and the Occident , is a term referring to the countries of Western Europe , the countries of the Americas, as well all countries of Northern and Central Europe, Australia and New Zealand...

, but marriages between first and second cousins nevertheless account for over 10% of marriages worldwide. They are particularly common in the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...

, where in some nations they account for over half of all marriages.

Only particular kinds of cousin marriage have been allowed in many cultures, such as between cross cousins. Various religions have ranged from prohibiting sixth cousins or closer from marrying to freely allowing first-cousin marriage. Cousin marriage has also featured prominently in the field of anthropology
Anthropology
Anthropology is the study of humanity. It has origins in the humanities, the natural sciences, and the social sciences. The term "anthropology" is from the Greek anthrōpos , "man", understood to mean mankind or humanity, and -logia , "discourse" or "study", and was first used in 1501 by German...

, notably in alliance theory
Alliance theory
The Alliance Theory is the name given to the structural method of studying kinship relations. It finds its origins in Claude Lévi-Strauss's Elementary Structures of Kinship , and is opposed to the functionalist theory of Radcliffe-Brown...

.

The children of first-cousin marriages have an increased risk of genetic disorders, though some scientists contend this is relatively small. Supporters of cousin marriage in the West may view legal bans as discrimination
Discrimination
Discrimination is the prejudicial treatment of an individual based on their membership in a certain group or category. It involves the actual behaviors towards groups such as excluding or restricting members of one group from opportunities that are available to another group. The term began to be...

, while opponents may appeal to morality or other arguments.

History

According to Professor Robin Fox
Robin Fox
Robin Fox is an Anglo-American anthropologist who has written on the topics of marriage, human and primate kinship systems, and evolutionary anthropology and sociology. He was born in Yorkshire. He founded the department of anthropology at Rutgers University in 1967 and remained a professor there...

 of Rutgers University, it is likely that 80% of all marriages in history have been between second cousins or closer. It is generally accepted that the founding population of Homo sapiens was small, anywhere from 700 to 10,000 individuals, and combined with the population dispersal caused by a hunter-gather existence, a certain amount of inbreeding would have been inevitable. Rates of first-cousin marriage in the United States, Europe and other Western countries like Brazil have declined since the 19th century, though even during that period they were not more than 3.63 percent of all unions in Europe. But in many other world regions cousin marriage is still strongly favored: in the Middle East some countries have seen the rate rise over previous generations, and one study finds quite stable rates among Indian Muslims over the past four decades.

Cousin marriage has often been chosen to keep cultural values intact through several generations, ensure the compatibility of spouses, and preserve familial wealth, sometimes via advantages relating to dowry
Dowry
A dowry is the money, goods, or estate that a woman brings forth to the marriage. It contrasts with bride price, which is paid to the bride's parents, and dower, which is property settled on the bride herself by the groom at the time of marriage. The same culture may simultaneously practice both...

 or bride price
Bride price
Bride price, also known as bride wealth, is an amount of money or property or wealth paid by the groom or his family to the parents of a woman upon the marriage of their daughter to the groom...

. Other reasons may include geographic proximity, tradition, strengthening of family ties, maintenance of family structure, a closer relationship between the wife and her in-laws, greater marital stability and durability, ease of prenuptial negotiations, enhanced female autonomy, the desire to avoid hidden health problems and other undesirable traits in a lesser-known spouse, and romantic love. Lower domestic violence and divorce rates have also been claimed. Many such marriages are arranged
Arranged marriage
An arranged marriage is a practice in which someone other than the couple getting married makes the selection of the persons to be wed, meanwhile curtailing or avoiding the process of courtship. Such marriages had deep roots in royal and aristocratic families around the world...

 and facilitated by other extended family
Extended family
The term extended family has several distinct meanings. In modern Western cultures dominated by nuclear family constructs, it has come to be used generically to refer to grandparents, uncles, aunts, and cousins, whether they live together within the same household or not. However, it may also refer...

 members.

United States

Cousin marriage was legal in all States prior to the Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

. However, according to Kansas sociology professor Martin Ottenheimer, after the Civil War the main purpose of marriage prohibitions was increasingly seen as less maintaining the social order and upholding religious morality and more as safeguarding the creation of fit offspring. Indeed, writers such as Noah Webster
Noah Webster
Noah Webster was an American educator, lexicographer, textbook pioneer, English spelling reformer, political writer, editor, and prolific author...

 and ministers like Philip Milledoler
Philip Milledoler
Philip Milledoler was a minister and the fifth President of Rutgers College serving from 1825 until 1840.-Biography:Philip Milledoler was born in 1775 in Rhinebeck, New York...

 and Joshua McIlvaine helped lay the groundwork for such viewpoints well before 1860. This led to a gradual shift in concern from affinal unions, like those between a man and his deceased wife's sister, to consanguineous unions. By the 1870s, Lewis Henry Morgan was writing about "the advantages of marriages between unrelated persons" and the necessity of avoiding "the evils of consanguine marriage," withdrawal from which would "increase the vigor of the stock." Cousin marriage to Morgan, and more specifically parallel-cousin marriage, was a remnant of a more primitive stage of human social organization. Morgan himself had married his mother's brother's daughter (first cousin) in 1851.

In 1846 the Governor of Massachusetts appointed a commission to study "idiots" in the state which implicated cousin marriage as being responsible for idiocy. Within the next two decades numerous reports appeared coming to similar conclusions, including for example by the Kentucky Deaf and Dumb Asylum, which concluded that cousin marriage resulted in deafness, blindness, and idiocy. Perhaps most important was the report of physician S.M. Bemiss for the American Medical Association
American Medical Association
The American Medical Association , founded in 1847 and incorporated in 1897, is the largest association of medical doctors and medical students in the United States.-Scope and operations:...

, which concluded "that multiplication of the same blood by in-and-in marrying does incontestably lead in the aggregate to the physical and mental depravation of the offspring." Despite being contradicted by other studies like those of George Darwin
George Darwin
Sir George Howard Darwin, FRS was an English astronomer and mathematician.-Biography:Darwin was born at Down House, Kent, the second son and fifth child of Charles and Emma Darwin...

 and Alan Huth in England and Robert Newman in New York, the report's conclusions were widely accepted.

These developments led to thirteen states and territories passing cousin marriage prohibitions by the 1880s. Though contemporaneous, the eugenics movement did not play much direct role in the bans, and indeed George Louis Arner in 1908 considered them a clumsy and ineffective method of eugenics, which he thought would eventually be replaced by more refined techniques. Ottenheimer considers both the bans and eugenics to be "one of several reactions to the fear that American society might degenerate." In any case, by the period up until the mid-1920s the number of bans had more than doubled. Since that time, the only three states to successfully add this prohibition are Kentucky in 1943, Maine in 1985, and Texas in 2005. The NCCUSL
National Conference of Commissioners on Uniform State Laws
The National Conference of Commissioners on Uniform State Laws is a non-profit, unincorporated association commonly referred to as the U.S. Uniform Law Commission. It consists of commissioners appointed by each state, the District of Columbia, the Commonwealth of Puerto Rico and the United States...

 unanimously recommended in 1970 that all such laws should be repealed, but no state has dropped its prohibition since the mid-1920s.

Europe

Only Austria, Hungary, and Spain banned cousin marriage throughout the 19th century, with dispensations being available from the government in the last two countries. Although Protestant
Protestantism
Protestantism is one of the three major groupings within Christianity. It is a movement that began in Germany in the early 16th century as a reaction against medieval Roman Catholic doctrines and practices, especially in regards to salvation, justification, and ecclesiology.The doctrines of the...

, the Church of Sweden
Church of Sweden
The Church of Sweden is the largest Christian church in Sweden. The church professes the Lutheran faith and is a member of the Porvoo Communion. With 6,589,769 baptized members, it is the largest Lutheran church in the world, although combined, there are more Lutherans in the member churches of...

 didn't ban first-cousin marriage until 1680 and required dispensation until 1844. England maintained a small but stable proportion of cousin marriages for centuries, with proportions in 1875 estimated by George Darwin at 3.5 percent for the middle classes and 4.5 percent for the nobility, though this has declined to under 1 percent in the 20th century. Queen Victoria and Prince Albert were a preeminent example.

The 19th century academic debate on cousin marriage evolved differently in Europe than it did in America. Despite the writings of Scottish deputy commissioner for lunacy Arthur Mitchell that cousin marriage had injurious effects on offspring, these conclusions were largely contradicted by researchers like Alan Huth and George Darwin. (At one point Mitchell had claimed that inbreeding in Scottish fishing communities led to a lower average hat size of six and seven-eighths, a quarter inch less than their more outbred neighbors.) In fact, Mitchell's own data did not support his hypotheses, prompting him to later speculate that the dangers of consanguinity
Consanguinity
Consanguinity refers to the property of being from the same kinship as another person. In that respect, consanguinity is the quality of being descended from the same ancestor as another person...

 might be partly overcome by proper living. Later studies by George Darwin found only much smaller effects that closely resemble those estimated today. His father Charles Darwin had initially speculated that cousin marriage might pose serious risks, but perhaps in response to his son's work, these thoughts were omitted from a later version of the book in which they had been published. When a question about cousin marriage was eventually considered in 1871 for the census, according to George Darwin it was rejected "amid the scornful laughter of the House, on the grounds that the idle curiosity of philosophers was not to be satisfied."

First-cousin marriage was legal in ancient Rome from at least the Second Punic War
Second Punic War
The Second Punic War, also referred to as The Hannibalic War and The War Against Hannibal, lasted from 218 to 201 BC and involved combatants in the western and eastern Mediterranean. This was the second major war between Carthage and the Roman Republic, with the participation of the Berbers on...

 (218–201 BC) to its ban by the Christian emperor Theodosius I
Theodosius I
Theodosius I , also known as Theodosius the Great, was Roman Emperor from 379 to 395. Theodosius was the last emperor to rule over both the eastern and the western halves of the Roman Empire. During his reign, the Goths secured control of Illyricum after the Gothic War, establishing their homeland...

 in 381 AD in the west and until after Justinian (d. 565 AD) in the east. However whether the incidence of such marriages was low or high has been debated. Anthropologist Jack Goody
Jack Goody
Sir John Rankine Goody is a British social anthropologist. He has been a prominent teacher at Cambridge University, he was elected Fellow of the British Academy in 1976, and he is an associate of the US National Academy of Sciences...

 advanced the position that cousin marriage was a typical pattern in Rome based on the marriage of four children of Emperor Constantine to their first cousins and what he considers the dubious nature of writings by Plutarch
Plutarch
Plutarch then named, on his becoming a Roman citizen, Lucius Mestrius Plutarchus , c. 46 – 120 AD, was a Greek historian, biographer, essayist, and Middle Platonist known primarily for his Parallel Lives and Moralia...

 and Livy
Livy
Titus Livius — known as Livy in English — was a Roman historian who wrote a monumental history of Rome and the Roman people. Ab Urbe Condita Libri, "Chapters from the Foundation of the City," covering the period from the earliest legends of Rome well before the traditional foundation in 753 BC...

 indicating the proscription of cousin marriage in the early Republic. Professors Brent Shaw
Brent Shaw
Brent D. Shaw is an historian who teaches ancient history at Princeton University.Shaw earned his B.A. and M.A. from the University of Alberta in 1968 and 1971, respectively, and then later his Ph.D...

 and Richard Saller, however, counter in their more comprehensive treatment that cousin marriages were never habitual or preferred in the western empire: for example, in one set of six stemma belonging to Roman aristocrats in the two centuries after Octavian, out of 33 marriages none were between first or second cousins. Shaw, Saller and Goody mutually agree that such marriages certainly carried no social stigma in the late Republic and early Empire. They cite the example of Cicero attacking Mark Antony, who married his father's brother's daughter, and note that if Cicero could have cast aspersions on Antony using this fact he surely would have. Instead the attack was exclusively directed against Antony's divorce.

Shaw and Saller propose in their thesis of low cousin marriage rates that as families from different regions were incorporated into the imperial Roman nobility, exogamy
Exogamy
Exogamy is a social arrangement where marriage is allowed only outside of a social group. The social groups define the scope and extent of exogamy, and the rules and enforcement mechanisms that ensure its continuity. In social studies, exogamy is viewed as a combination of two related aspects:...

 was necessary to accommodate them and avoid destabilizing the Roman social structure. Their data from tombstones further indicates that in most of the western empire parallel-cousin marriages were also not widely practiced among commoners. Spain and Noricum
Noricum
Noricum, in ancient geography, was a Celtic kingdom stretching over the area of today's Austria and a part of Slovenia. It became a province of the Roman Empire...

 were exceptions to this rule, but even there the percentages did not rise above ten percent. They further point out that since property belonging to the nobility was typically fragmented, keeping current assets in the family offered no special advantage compared with acquiring it by intermarriage. Jack Goody claimed that early Catholic marriage rules forced a sharp change from earlier norms in order to deny heirs to the wealthy and therefore increase the chance they would will their property to the Church. But Shaw and Saller believe the Church often merely took the place of the earlier position of the emperor in acquiring the inheritance of aristocrats who lacked heirs, instead averring that the Catholic injunctions against cousin marriage were due more to ideology than any conscious desire to acquire wealth.

For some prominent examples of cousin marriages in ancient Rome, such as the marriage of Octavian's daughter to his sister's son, see the Julio-Claudian family tree
Julio-Claudian family tree
The Julio-Claudian dynasty of the early Roman Empire has a family tree complicated by multiple marriages between the members of the gens Julia and the gens Claudia.-Family tree:...

. Marcus Aurelius also married his maternal first cousin Faustina the Younger
Faustina the Younger
Annia Galeria Faustina Minor , Faustina Minor or Faustina the Younger was a daughter of Roman Emperor Antoninus Pius and Roman Empress Faustina the Elder. She was a Roman Empress and wife to her maternal cousin Roman Emperor Marcus Aurelius...

 and had 13 children. Cousin marriage was more frequent in Ancient Greece
Ancient Greece
Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...

, and in fact marriages with the niece were also permitted there, one example of which was King Leonidas I of Sparta who married his half-niece. A Greek woman who became epikleros
Epikleros
Epikleros was the term used to describe an heiress in ancient Athens, and in other ancient Greek city states. It denoted a daughter of a man who had no male heirs. In Sparta they were called patroiouchoi , as they were in Gortyn...

, or heiress with no brothers, was obliged to marry her father's nearest male kin if she had not yet married and given birth to a male heir; first in line would be either her father's brothers or their sons, followed by her father's sisters' sons. According to Goody, cousin marriage was also not forbidden in the newly Christian and presumably pre-Christian Ireland, where an heiress was also obligated to marry a paternal cousin. From the 7th century the Irish Church only recognized four degrees of prohibited kinship, and civil law fewer. This persisted until after the Norman conquests and the synod
Synod
A synod historically is a council of a church, usually convened to decide an issue of doctrine, administration or application. In modern usage, the word often refers to the governing body of a particular church, whether its members are meeting or not...

 at Cashel
Cashel, County Tipperary
Cashel is a town in South Tipperary in Ireland. Its population was 2936 at the 2006 census. The town gives its name to the ecclesiastical province of Cashel. Additionally, the cathedra of the Roman Catholic Archdiocese of Cashel and Emly was originally in the town prior to the English Reformation....

 in 1101. In contrast, contemporary British law was based on official Catholic policy, and Anglo-Norman clergy often became disgusted with the Irish "law of fornication." Finally, Edward Westermarck states that marriage among the ancient Teutons
Teutons
The Teutons or Teutones were mentioned as a Germanic tribe by Greek and Roman authors, notably Strabo and Marcus Velleius Paterculus and normally in close connection with the Cimbri, whose ethnicity is contested between Gauls and Germani...

 was apparently prohibited only in the ascending and descending lines and among siblings.

Middle East

Cousin marriage has been at least allowed throughout the Middle East for all recorded history. Anthropologists have debated the significance of the practice; some view it as the defining feature of the Middle Eastern kinship system while others note that overall rates of cousin marriage have varied sharply between different Middle Eastern communities. There is very little numerical evidence of rates of cousin marriage in the past. In many cases there is not only a preference but a right to marry the father's brother's daughter, wherein if the girl's family wishes to marry her to anyone else they must first get the permission of the father's brother's son.

Raphael Patai
Raphael Patai
Raphael Patai , born Ervin György Patai, was a Hungarian-Jewish ethnographer, historian, Orientalist and anthropologist.-Family background:...

 reports that in central Arabia no relaxation of a man's right to the father's brother daughter (FBD), seems to have taken place in the past hundred years before his 1962 work. Here the girl is not forced to marry her bint 'amm but she cannot marry another unless he gives consent. The force of the custom is seen in one case from Jordan when the father arranged for the marriage of his daughter to an outsider without obtaining the consent of her ibn 'amm. When the marriage procession progressed with the bride toward the house of the bridegroom, the ibn 'amm rushed forward, snatched away the girl, and forced her into his own house. This was regarded by all as a lawful marriage. In Iraq the right of the cousin has also traditionally been followed and a girl breaking the rule without the consent of the ibn 'amm could have ended up murdered by him. The Syrian city of Aleppo
Aleppo
Aleppo is the largest city in Syria and the capital of Aleppo Governorate, the most populous Syrian governorate. With an official population of 2,301,570 , expanding to over 2.5 million in the metropolitan area, it is also one of the largest cities in the Levant...

 during the 19th century featured a rate of cousin marriage among the elite of 24% according to one estimate, a figure that masked widespread variation: some leading families had none or only one cousin marriage, while others had rates approaching 70%. Cousin marriage rates were highest among women, merchant families, and older well-established families.

In-marriage was less frequent in the late pre-Islamic Hijaz than in ancient Egypt. It existed in Medina
Medina
Medina , or ; also transliterated as Madinah, or madinat al-nabi "the city of the prophet") is a city in the Hejaz region of western Saudi Arabia, and serves as the capital of the Al Madinah Province. It is the second holiest city in Islam, and the burial place of the Islamic Prophet Muhammad, and...

 during Muhammad's time but at less than today's rates. In Egypt estimates from the late 19th and early 20th century state variously that either 80 percent of fellahin married first cousins or two-thirds married them if they existed. One source from the 1830s states that cousin marriage was less common in Cairo
Cairo
Cairo , is the capital of Egypt and the largest city in the Arab world and Africa, and the 16th largest metropolitan area in the world. Nicknamed "The City of a Thousand Minarets" for its preponderance of Islamic architecture, Cairo has long been a centre of the region's political and cultural life...

 than in other areas. In traditional Palestine, if a girl had no ibn 'amm (father's brother's son) or he renounced his right to her, the next in line was traditionally the ibn khal (mother's brother's son) and then other relatives. Raphael Patai however reported that this custom loosened in the years preceding his 1947 study. In ancient Persia the Achaemenid kings habitually married their cousins and nieces, while between the 1940s and 1970s the percentage of Iranian cousin marriages increased from 34 to 44%. Cousin marriage among native Middle Eastern Jews is generally far higher than among the European Ashkenazim, who assimilated European marital practices after the diaspora
Diaspora
A diaspora is "the movement, migration, or scattering of people away from an established or ancestral homeland" or "people dispersed by whatever cause to more than one location", or "people settled far from their ancestral homelands".The word has come to refer to historical mass-dispersions of...

.

According to anthropologist Ladislav Holý
Ladislav Holý
Ladislav Holý was a Czech anthropologist and Africanist of the British school of social anthropology.- Early life :Holý studied anthropology and archaeology at the Charles' University in Prague, Czechoslovakia. There he met his future wife and research partner, Alice Sučíková, who accompanied him...

, cousin marriage is not an independent phenomenon but rather one expression of a wider Middle Eastern preference for agnatic solidarity, or solidarity with one's father's lineage. According to Holy the oft-quoted reason for cousin marriage of keeping property in the family is, in the Middle Eastern case, just one specific manifestation of keeping intact a family's whole "symbolic capital." Close agnatic marriage has also been seen as a result of the conceptualization of men as responsible for the control of the conduct of women. Honor is another reason for cousin marriage: while the natal family may lose influence over the daughter through marriage to an outsider, marrying her in their kin group allows them to help prevent dishonorable outcomes like either attacks on her or her own unchaste behavior. Pragmatic reasons for the husband, such as warmer relations with his father-in-law, and those for parents of both spouses, like reduced bride price and access to the labor of the daughter's children, also contribute. Throughout Middle Eastern history cousin marriage has been both praised and discouraged by various writers and authorities.

A 2009 study found that many Arab countries display some of the highest rates of consanguineous marriages in the world, and that first cousin marriages which may reach 25-30% of all marriages. In Qatar, Yemen, and UAE, consanguinity rates are increasing in the current generation. Research among Arabs and worldwide has indicated that consanguinity could have an effect on some reproductive health parameters such as postnatal mortality and rates of congenital malformations.

Origins of Middle Eastern parallel-cousin marriage

Islamization, along with an area's inclusion in the eighth-century Arab-Islamic Khalifate (and its persistence within the Islamic world) has been demonstrated by Korotayev to be a strong and significant predictor of parallel-cousin (Father's Brother's Daughter - FBD) marriage. He has shown that while there is a clear functional connection between Islam and FBD marriage, the prescription to marry a FBD does not appear to be sufficient to persuade people to actually marry thus, even if the marriage brings with it economic advantages. According to Korotayev, a systematic acceptance of parallel-cousin marriage took place when Islamization occurred together with Arabization.

Africa

Cousin marriage rates from most African nations outside the Middle East are unknown. It is however estimated that 35–50% of all sub-Saharan African populations either prefer or accept cousin marriages. In Nigeria, the most populous country of Africa, the three largest tribes in order of size are the Hausa
Hausa people
The Hausa are one of the largest ethnic groups in West Africa. They are a Sahelian people chiefly located in northern Nigeria and southeastern Niger, but having significant numbers living in regions of Cameroon, Ghana, Cote d'Ivoire, Chad and Sudan...

, Yoruba
Yoruba people
The Yoruba people are one of the largest ethnic groups in West Africa. The majority of the Yoruba speak the Yoruba language...

, and Igbo
Igbo people
Igbo people, also referred to as the Ibo, Ebo, Eboans or Heebo are an ethnic group living chiefly in southeastern Nigeria. They speak Igbo, which includes various Igboid languages and dialects; today, a majority of them speak English alongside Igbo as a result of British colonialism...

. The Hausa are overwhelmingly Muslim, though followers of traditional religions do exist. Muslim Hausa practice cousin marriage preferentially, and polygyny is allowed if the husband can support multiple wives. The book Baba of Karo
Baba of Karo
Baba of Karo is a 1954 book by the anthropologist Mary F. Smith. The book is an anthropological record of the Hausa people, partly compiled from an oral account given by Baba , the daughter of a Hausa farmer and Koranic teacher, and translated by Smith.Smith's husband, the anthropologist M. G...

 presents one prominent portrayal of Hausa life: according to its English coauthor, it is unknown for Hausa women to be unmarried for any great length of time after around the age of fourteen. Divorce can be accomplished easily by either the male or the female, but females must then remarry. Even for a man, lacking a spouse is looked down upon. Baba of Karo's first of four marriages was to her second cousin. She recounts in the book that her good friend married the friend's first cross cousin.

The Yoruba people are split between Islam and Christianity. A 1974 study analyzed Yoruba marriages in the town Oka Akoko, finding that among a sample of highly polygynous marriages having an average of about three wives, 51% of all pairings were consanguineous. These included not only cousin marriages but also uncle-niece unions. Reportedly it is a custom that in such marriages at least one spouse must be a relative, and generally such spouses were the preferred or favorite wives in the marriage and gave birth to more children. However, it must be emphasized that this was not a general study of Yoruba, but only of highly polygynous Yoruba residing in Oka Akoko. Finally, the Igbo people of southern Nigeria specifically prohibit both parallel- and cross-cousin marriage, though polygyny is common. Men are forbidden to marry within their own patrilineage or those of their mother or father's mother and must marry outside their own village. Igbo are almost entirely Christian, having converted heavily under colonialism.

In Ethiopia most of the population were historically rigidly opposed to cousin marriage, and could consider up to third cousins the equivalent of brother and sister, with marriage at least ostensibly prohibited out to sixth cousins. They also took affinal prohibitions very seriously. The prospect of a man marrying a former wife's "sister" was seen as incest, and conversely for a woman and her former husband's "brother." Though Muslims make up over a third of the Ethiopian population, and Islam has been present in the country since the time of Muhammad, cross-cousin marriage is very rare among most Ethiopian Muslims. In contrast to the Nigerian situation, in Ethiopia Islam cannot be identified with particular tribal groups and is found across most of them, and conversions between religions are comparatively common. But exceptions to these rules include the overwhelmingly Muslim Somali and Afar peoples, who respectively make up 6.2% and 1.73% of the population. The Afar practice a form of cousin marriage called absuma that is arranged at birth and can be forced.

China

Confucius described marriage as "the union of two surnames, in friendship and in love." In ancient China there is evidence that in some cases two clans had a longstanding arrangement wherein they would only marry members of the other clan. Some men also practiced sororate marriage
Sororate marriage
Sororate marriage is a type of marriage in which a husband engages in marriage or sexual relations with the sister of his wife, usually after the death of his wife, or once his wife has proven infertile....

, that is, a marriage to a former wife's sister or a polygynous marriage to both sisters. This would have the effect of eliminating parallel-cousin marriage as an option but would leave cross-cousin marriage acceptable. In the ancient system of the Erya
Erya
The Erya is the oldest extant Chinese dictionary or Chinese encyclopedia. Bernhard Karlgren concluded that "the major part of its glosses must reasonably date from" the 3rd century BC....

 dating from around the 3rd century B.C., the words for the two types of cross cousins were identical, with father's brother's children and mother's sister's children both being distinct. However, it is evident that whereas it may not have been permissible at that time, marriage with the mother's sister's children also became possible by the third century A.D. Eventually the mother's sister's children and cross cousins shared one set of terms, with only the father's brother's children retaining a separate set. This usage remains today, with biao cousins considered "outside" and paternal tang cousins being of the same house. There were also some periods in Chinese history where all cousin marriage was legally prohibited, as law codes dating from the Ming Dynasty attest. However, enforcement proved difficult and by the subsequent Qing Dynasty the former laws had been restored.

The following is a Chinese poem by Po Chu-yi (A.D. 772–846).
In Ku-feng hsien, in the district of Ch'u chou [Kiangsu]
Is a village called Chu Ch'en [the names of the two clans].
There are only two clans there
Which have intermarried for many generations.


Anthropologist Francis Hsu described mother's brother's daughter as being the most preferred type of Chinese cousin marriage, mother's sister's daughter as being tolerated, and father's sister's daughter (FZD) as being disfavored. Some writers report this last form as being nearly incestuous. One proposed explanation is that in FZD marriage the daughter does not change her surname throughout her life, so the marriage does not result in an extension of the father's kinship ties. In Chinese culture these patrilineal ties are most important in determining the closeness of a relation. In the case of the MZD marriage there are no such ties and consequently this may not even be viewed as cousin marriage. Finally, one reason that MBD marriage is often most common may be the typically greater emotional warmth between a man and his mother's side of the family. Later analyses have found regional variation in these patterns: in some rural areas where cousin marriage is still common, MBD is not preferred but merely acceptable, similar to MZD. By the early to mid-twentieth century, anthropologists described cross-cousin marriage in China as "still permissible...but...generally obsolete" or as "permitted but not encouraged."

Current status

Slightly over 10% of all marriages worldwide are estimated to be between second cousins or closer. As of 2001, here is one estimate for the percentages of world population living in countries with various levels of consanguineous marriage: less than 1% consanguinity, 18%, 1–10% consanguinity, 47%, 10–50+% consanguinity, 17%, and unknown, 18%. The overall rate appears to be declining.

Middle East

The Middle East has uniquely high rates of cousin marriage among the world's regions. Certain Middle Eastern countries, including Saudi Arabia
Saudi Arabia
The Kingdom of Saudi Arabia , commonly known in British English as Saudi Arabia and in Arabic as as-Sa‘ūdiyyah , is the largest state in Western Asia by land area, constituting the bulk of the Arabian Peninsula, and the second-largest in the Arab World...

, have rates of marriage to first or second cousins that may exceed 50%. Iraq
Iraq
Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....

 was estimated in one study to have a rate of 33%, and figures for Iran
Iran
Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...

 and Afghanistan
Afghanistan
Afghanistan , officially the Islamic Republic of Afghanistan, is a landlocked country located in the centre of Asia, forming South Asia, Central Asia and the Middle East. With a population of about 29 million, it has an area of , making it the 42nd most populous and 41st largest nation in the world...

 have been estimated in the range of 30–40%. Though on the lower end, Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...

 and Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

 nevertheless have rates above 20%.

All states in the Persian Gulf currently require advance genetic screening for all prospective married couples. Qatar was the last Gulf nation to institute mandatory screening in 2009, mainly to warn related couples who are planning marriage about any genetic risks they may face. The current rate of cousin marriage there is 54%, an increase of 12–18% over the previous generation. A report by the Dubai-based Centre for Arab Genomic Studies (CAGS) in September 2009 found that Arabs have one of the world's highest rates of genetic disorders, nearly two-thirds of which are linked to consanguinity. Research from CAGS and others suggests consanguinity is declining in Lebanon
Lebanon
Lebanon , officially the Republic of LebanonRepublic of Lebanon is the most common term used by Lebanese government agencies. The term Lebanese Republic, a literal translation of the official Arabic and French names that is not used in today's world. Arabic is the most common language spoken among...

 and Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...

 and among Palestinians, but is increasing in Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...

, Mauritania
Mauritania
Mauritania is a country in the Maghreb and West Africa. It is bordered by the Atlantic Ocean in the west, by Western Sahara in the north, by Algeria in the northeast, by Mali in the east and southeast, and by Senegal in the southwest...

 and Sudan
Sudan
Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...

.

Dr. Ahmad Teebi, a genetics and pediatrics professor at Weill Cornell Medical College in Qatar, links the increase in cousin marriage in Qatar and other Gulf states to tribal tradition and the region’s expanding economies. “Rich families tend to marry rich families, and from their own – and the rich like to protect their wealth,” he said. “So it’s partly economic, and it’s also partly cultural.” In regard to the higher rates of genetic disease in these societies, he says: "It's certainly a problem," but also that "The issue here is not the cousin marriage, the issue here is to avoid the disease."

In many Middle Eastern nations a marriage to the father's brother's daughter (FBD) is considered ideal, though this type may not always actually outnumber other types. One anthropologist, Ladislav Holý
Ladislav Holý
Ladislav Holý was a Czech anthropologist and Africanist of the British school of social anthropology.- Early life :Holý studied anthropology and archaeology at the Charles' University in Prague, Czechoslovakia. There he met his future wife and research partner, Alice Sučíková, who accompanied him...

, argues that it is important to distinguish between the ideal of FBD marriage and marriage as it is actually practiced, which always also includes other types of cousins and unrelated spouses. Holý cites the Berti people of the Sudan, who consider the FBD to be the closest kinswoman to a man outside of the prohibited range. If there is more than one relationship between spouses, as often results from successive generations of cousin marriage, only the patrilineal one is counted. Marriage within the lineage is preferred to marriage outside the lineage even when no exact genealogical
Genealogy
Genealogy is the study of families and the tracing of their lineages and history. Genealogists use oral traditions, historical records, genetic analysis, and other records to obtain information about a family and to demonstrate kinship and pedigrees of its members...

 relationship is known. Of 277 first marriages, only 84 were between couples unable to trace any genealogical relationship between them. Of those, in 64 the spouses were of the same lineage. However, of 85 marriages to a second or third wife, in 60 the spouses were of different lineages. The Marri
Marri
Marri ) is one of the largest ethnic Baloch tribes in Balochistan and Sindh provinces of Pakistan. Marri was considered to be a clan of the Rind tribe in the early history of Baloch and Balochistan...

 have a very limited set of incest prohibitions that includes only lineal relatives, the sister, and aunts except the mother's brother's wife. Female members of the mother's lineage are seen as only loosely related. Finally there are the Baggara
Baggara
The Baggāra Arabs are a set of communities inhabiting the portion of Africa's Sahel between Lake Chad and southern Kordofan, numbering over one million. They have a common language which is one of the regional colloquial Arabic languages...

 Arabs who favor MBD marriage first, followed by cross-cousin marriage if the cross cousin is a member of the same surra, a group of agnates of five or six generations depth. Next is marriage within the surra. There is no preference for marriages between matrilateral parallel cousins.

South Asia

Attitudes in India on cousin marriage vary sharply by region and culture. For Muslims it is acceptable and legal to marry a first cousin. But for Hindus it may be illegal under the 1955 Hindu Marriage Act
Hindu Marriage Act
The Hindu Marriage Act was established in 1955 as part of the Hindu Code Bills. Three other important acts were also created during this time and they include the Hindu Succession Act , the Hindu Minority and Guardianship Act , and the Hindu Adoptions and Maintenance Act...

, though the specific situation is more complex. The Hindu Marriage Act makes cousin marriage illegal for Hindus with the exception of marriages permitted by regional custom. Practices of the small Christian minority are also location dependent: their cousin marriage rates are higher in southern states like Karnataka
Karnataka
Karnataka , the land of the Kannadigas, is a state in South West India. It was created on 1 November 1956, with the passing of the States Reorganisation Act and this day is annually celebrated as Karnataka Rajyotsava...

 with high overall rates.

Cousin marriage is proscribed and seen as incest for Hindus in north India. In fact it may even be unacceptable to marry within one's village or for two siblings to marry partners from the same village. The northern kinship model prevails in the states of Rajasthan
Rajasthan
Rājasthān the land of Rajasthanis, , is the largest state of the Republic of India by area. It is located in the northwest of India. It encompasses most of the area of the large, inhospitable Great Indian Desert , which has an edge paralleling the Sutlej-Indus river valley along its border with...

, Gujarat, Uttar Pradesh
Uttar Pradesh
Uttar Pradesh abbreviation U.P. , is a state located in the northern part of India. With a population of over 200 million people, it is India's most populous state, as well as the world's most populous sub-national entity...

, Haryana
Haryana
Haryana is a state in India. Historically, it has been a part of the Kuru region in North India. The name Haryana is found mentioned in the 12th century AD by the apabhramsha writer Vibudh Shridhar . It is bordered by Punjab and Himachal Pradesh to the north, and by Rajasthan to the west and south...

, and Punjab. But in south India it is common for Hindu cross cousins to marry, with matrilateral
Matrilateral
The term Matrilateral describes kin 'on the mother's side'.Social anthropologists have underlined that even where a social group demonstrates a strong emphasis on one or other line of inheritance , relatives who fall outside this unilineal grouping will not simply be ignored...

 cross-cousin (mother's brother's daughter) marriages being especially favored. The southern kinship model prevails in the states of Kerala
Kerala
or Keralam is an Indian state located on the Malabar coast of south-west India. It was created on 1 November 1956 by the States Reorganisation Act by combining various Malayalam speaking regions....

, Tamil Nadu
Tamil Nadu
Tamil Nadu is one of the 28 states of India. Its capital and largest city is Chennai. Tamil Nadu lies in the southernmost part of the Indian Peninsula and is bordered by the union territory of Pondicherry, and the states of Kerala, Karnataka, and Andhra Pradesh...

, Karnataka
Karnataka
Karnataka , the land of the Kannadigas, is a state in South West India. It was created on 1 November 1956, with the passing of the States Reorganisation Act and this day is annually celebrated as Karnataka Rajyotsava...

, and Andhra Pradesh
Andhra Pradesh
Andhra Pradesh , is one of the 28 states of India, situated on the southeastern coast of India. It is India's fourth largest state by area and fifth largest by population. Its capital and largest city by population is Hyderabad.The total GDP of Andhra Pradesh is $100 billion and is ranked third...

. South Indian women have been described as having more personal autonomy than North Indian women and a kinship system leaving women closer to their families of origin and not based on patrilineal descent may explain both this and somewhat lower South Indian birth rates. In the exogamous north, a woman will not usually be in a position to help her family after marriage, since the house of her husband is likely to be far away. Female children are consequently less valued. In the South Indian system males are also likely to enter into arrangements that include males related by marriage, whereas in the north such relationships are more defined by blood ties. But the higher the caste in south India, in general the closer the position of females is to that under the northern system.

In India, especially in Rajasthani Maheshwari community there is a special rule, which automatically rules out possibilities of cousin marriage. Everyone is immediately associated with 4 surnames 1.own surname, 2.mother's previous surname, 3.father's mother's previous surname, 4.mother's mother's previous surname. These 4 surnames are known as the candidate's SAKHA. Any 2 candidates who want to marry cannot have any SAKHA in common. The marriage is allowed only when all these 4 SAKHA are different for both the candidates. This automatically rules out closer cousin marriages. Although this is a very effective system, it is not observed in other communities in India. This also rules out Intra-Gotra marriages. Also, in this community, if the origin of two candidates is same and known, the marriage is not allowed if the origin is within 7 generations.

Practices in central India overall are closer to the northern model than the southern, but differences exist from each. For example, in Mumbai
Mumbai
Mumbai , formerly known as Bombay in English, is the capital of the Indian state of Maharashtra. It is the most populous city in India, and the fourth most populous city in the world, with a total metropolitan area population of approximately 20.5 million...

, studies done in 1956 showed 7.7% of Hindus married to a second cousin or closer. By contrast, in the northern city of New Delhi
New Delhi
New Delhi is the capital city of India. It serves as the centre of the Government of India and the Government of the National Capital Territory of Delhi. New Delhi is situated within the metropolis of Delhi. It is one of the nine districts of Delhi Union Territory. The total area of the city is...

 only 0.1% of Hindus were married to a first cousin during the 1980s. At the other extreme, studies done in the South Indian province of Karnataka, which contains Bangalore
Bangalore
Bengaluru , formerly called Bengaluru is the capital of the Indian state of Karnataka. Bangalore is nicknamed the Garden City and was once called a pensioner's paradise. Located on the Deccan Plateau in the south-eastern part of Karnataka, Bangalore is India's third most populous city and...

, during that period show fully one third of Hindus married to a second cousin or closer. Pre-2000 Madhya Pradesh
Madhya Pradesh
Madhya Pradesh , often called the Heart of India, is a state in central India. Its capital is Bhopal and Indore is the largest city....

, from which Chhattisgarh
Chhattisgarh
Chhattisgarh is a state in Central India, formed when the 16 Chhattisgarhi-speaking South-Eastern districts of Madhya Pradesh gained separate statehood on 1 November 2000....

 has now split, and Maharashtra
Maharashtra
Maharashtra is a state located in India. It is the second most populous after Uttar Pradesh and third largest state by area in India...

, which contains Mumbai, are provinces that are intermediate in their kinship practices.

India's Muslim minority represents about 12% of its population (excluding Jammu and Kashmir) and has an overall rate of cousin marriage of 22% according to a 2000 report. Most Muslim cousin marriages were between first cousins, with the rate of first-cousin marriage being 20%. Muslim consanguinity in north India was typical, but below the overall northern statistic lies a sharply divided picture: Jammu and Kashmir is the only Indian state with a Muslim majority, with a Muslim consanguinity rate of 40%, while at the other extreme Haryana, though its population is 17% Muslim, has a Muslim consanguinity rate of only 1%. This dichotomy may be a legacy of the partition of the sub-continent into India and Pakistan, when there was substantial Muslim migration to Pakistan from the eastern parts of the former unified state of Punjab. In south India by contrast the rates are fairly constant, except for the South Indian Malabar Muslims of Kerala (9%) who claim descent from Arab traders who settled permanently in India in the 8th century. Most Indian Muslims by contrast are the result of Hindu conversions to Islam in the 16th century or later. The lowest rate for a whole Indian region was in East India (15%). Consanguinity rates were generally stable across the four decades for which data exists, though second-cousin marriage appears to have been decreasing in favor of first-cousin marriage.

In Pakistan there is the concept of biradari or "brotherhood," whose members may or may not be related. Each biradari usually has an associated caste (zat
Caste system among South Asian Muslims
Caste system among South Asian Muslims refers to units of social stratification that have developed among Muslims in South Asia.Religious, historical and socio-cultural factors have helped define the bounds of endogamous groups for Muslims in South Asia...

) name. It has been proposed that one of the features underlying cousin marriage in Pakistan is caste endogamy
Endogamy
Endogamy is the practice of marrying within a specific ethnic group, class, or social group, rejecting others on such basis as being unsuitable for marriage or other close personal relationships. A Greek Orthodox Christian endogamist, for example, would require that a marriage be only with another...

. According to this interpretation, marrying within the extended family allows Muslim Pakistanis to maintain caste differences while differentiating themselves from the exogamous Hindus of neighboring North India.

In 2005, BBC News reported estimates that at least 55% of British Pakistanis are married to first cousins, and that British Pakistanis are 13 times more likely to have children with recessive disorders than the general population. This prompted calls from Labour MP Ann Cryer for an end to the practice of cousin marriage. Local doctors in Ms Cryer's constituency estimate that three quarters of marriages in the Pakistani community are between first cousins. Ms. Cryer said, "As we address problems of smoking, drinking, obesity, we say it's a public health issue, and therefore we all have to get involved with it in persuading people to adopt a different lifestyle. ... I think the same should be applied to this problem in the Asian community. They must adopt a different lifestyle. ... They must look outside the family for husbands and wives for their young people."

United States

The United States has the only bans on cousin marriage in the Western world. , 30 U.S. states prohibit most or all marriage between first cousins, and a bill is pending in Maryland which would prohibit most first cousins from marrying there. Six states prohibit first-cousin-once-removed marriages. Some states prohibiting cousin marriage recognize cousin marriages performed in other states, but despite occasional claims that this holds true in general, laws also exist that explicitly void all foreign cousin marriages or marriages conducted by state residents out of state.

Data on cousin marriage in the United States is sparse. It was estimated in 1960 that 0.2% of all marriages between Roman Catholics were between first or second cousins, but no more recent nationwide studies have been performed. It is unknown what proportion of that number were first cousins, which is the group facing marriage bans. To contextualize the group's size, the total proportion of interracial marriages in 1960, the last census year before the end of anti-miscegenation statutes, was 0.4%, and the proportion of black-white marriages was 0.13%. While recent studies have cast serious doubt on whether cousin marriage is as dangerous as is popularly assumed, professors Diane B. Paul and Hamish G. Spencer speculate that legal bans persist in part due to "the ease with which a handful of highly motivated activists—or even one individual—can be effective in the decentralized American system, especially when feelings do not run high on the other side of an issue."

Among supporters of repealing the laws, the Cousin Couples organization describes itself as "the world's primary resource for romantic relationships among cousins including cousin marriage." This group likens laws against cousin marriage to the anti-miscegenation laws
Anti-miscegenation laws
Anti-miscegenation laws, also known as miscegenation laws, were laws that enforced racial segregation at the level of marriage and intimate relationships by criminalizing interracial marriage and sometimes also sex between members of different races...

 of decades past. Their website includes legal and religious information and a message board.

A bill to repeal the ban on first-cousin marriage in Minnesota was introduced by Phyllis Kahn
Phyllis Kahn
Phyllis Kahn is a retired professor of Biophysics and a DFL member of the Minnesota House of Representatives, serving District 59B, which includes portions of the city of Minneapolis in Hennepin County, which is in the Twin Cities metropolitan area. Educated at Cornell , Yale Phyllis Kahn (born...

 in 2003, but it died in committee. Republican Minority Leader Marty Seifert criticized the bill in response, saying it would "turn us into a cold Arkansas." According to the University of Minnesota's The Wake, Kahn was aware the bill had little chance of passing but introduced it anyway to draw attention to the issue. She reportedly got the idea after learning that cousin marriage is an acceptable form of marriage among some cultural groups that have a strong presence in Minnesota, namely the Hmong
Hmong people
The Hmong , are an Asian ethnic group from the mountainous regions of China, Vietnam, Laos, and Thailand. Hmong are also one of the sub-groups of the Miao ethnicity in southern China...

 and Somali
Somali people
Somalis are an ethnic group located in the Horn of Africa, also known as the Somali Peninsula. The overwhelming majority of Somalis speak the Somali language, which is part of the Cushitic branch of the Afro-Asiatic language family...

.

In contrast, Maryland delegates Henry B. Heller
Henry B. Heller
Henry B. "Hank" Heller is an American politician from the state of Maryland. A Democrat, he is currently one of three members of the Maryland House of Delegates representing District 19 in central Montgomery County.-Background:...

 and Kumar P. Barve
Kumar P. Barve
Kumar P. Barve is an American politician. He is a member of the Maryland House of Delegates, representing district 17 in Montgomery County.-Legislative career:...

 sponsored a bill to ban first-cousin marriages in 2000. It got further than Kahn's bill, passing the House of Delegates by 82 to 46 despite most Republicans voting no, but finally died in the state Senate. In response to the 2005 marriage of Pennsylvanian first cousins Eleanor Amrhein and Donald W. Andrews Sr. in Maryland, Heller said that he might resurrect the bill because such marriages are "like playing genetic roulette."

Texas actually did pass a ban on first-cousin marriage the same year as Amrhein and Andrews married, evidently in reaction to the presence of the polygamous FLDS. Texas Representative Harvey Hilderbran
Harvey Hilderbran
Harvey Ray Hilderbran is a Republican member of the Texas House of Representatives from District 53, which includes fifteen central Texas counties. Hilderbran resides in Kerrville west of San Antonio.-Legislative matters:Rep...

, whose district includes the main FLDS compound, authored an amendment to a child protection statute to both discourage the FLDS from settling in Texas and to "prevent Texas from succumbing to the practices of taking child brides, incest, welfare abuse and domestic violence." While Hilderbran stated that he would not have authored a bill solely to ban first-cousin marriage, he also said in an interview that "Cousins don’t get married just like siblings don’t get married. And when it happens you have a bad result. It’s just not the accepted normal thing." Some news sources then only mentioned the polygamy and child abuse provisions and ignored the cousin marriage portion of the bill, as did some more recent sources as well. The new statute makes sex with an adult first cousin a more serious felony than with adult members of one's immediate family.

The U.S. state of Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...

 allows first-cousin marriage if the couple agrees to have genetic counseling, while North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

 allows it so long as the applicants for marriage are not rare double first cousins, meaning cousins through both parental lines. In the other 25 states permitting at least some first-cousin marriage, double cousins are not distinguished.

States have various laws regarding cousin marriage and other close relatives, State laws regarding cousin marriage as well as defined laws on status, including whether or not you are a half-cousin, double cousin, infertile, over 65, or whether its a tradition prevalent in a native or ancestry culture, adoption status, in-law, whether or not you need genetic counseling, and whether you are allowed to marry a first cousin once removed.

United Kingdom

There has been a great deal of debate in the past few years in the United Kingdom about whether to discourage cousin marriages through government public relations campaigns or ban them entirely. The debate has been prompted by a Pakistani immigrant population making up 1.5% of the British population, of whom about 55% marry a first cousin. For example, Environment Minister (later Immigration Minister) Phil Woolas
Phil Woolas
Philip James Woolas was a British Labour Party politician who was the Member of Parliament for Oldham East and Saddleworth from his election in 1997 to 2010. He was the Minister of State for Borders and Immigration in the Home Office, as well as being the Minister of State for the Treasury...

 said in 2008, "If you have a child with your cousin the likelihood is there'll be a genetic problem" and that such marriages were the "elephant in the room
Elephant in the room
"Elephant in the room" is an English metaphorical idiom for an obvious truth that is being ignored or goes unaddressed. The idiomatic expression also applies to an obvious problem or risk no one wants to discuss....

." Muslim physician Mohammad Walji has spoken out against the practice, saying that it is a "very significant" cause of infant death, and his practice has produced leaflets warning against it. But in sharp contrast, Professor Alan Bittles of the Centre for Comparative Genomics in Australia states that the risk of birth defects rises from roughly 2% in the general population to 4% for first cousins and therefore that "It would be a mistake to ban it." Researcher Aamra Darr of the University of Leeds
University of Leeds
The University of Leeds is a British Redbrick university located in the city of Leeds, West Yorkshire, England...

 has also criticized what she called an "alarmist presentation of data" that exaggerates the risk.

There is evidence that the rate of cousin marriage has increased among British Pakistanis from rates in their parents' generation. Most British Pakistani marriages are arranged, but these can be of two types: conventionally arranged marriages where the bride and groom have little or no say, and what some British Pakistanis describe as "arranged love marriages" where the bride and groom play an important role. The latter are less frequent but their number is increasing. Among traditional arranged marriages the outcome typically depends on the balance of power between parents and the number of cousins on each side of the family; each parent may try to sway cousin marriages to their respective side. Parents usually first consider the claims of their own close kin, especially siblings, upon their offspring as spouses. Those who violate these obligations can be accused of being lalchi or greedy.

Among British Pakistanis most marriages are transnational and have the effect of bringing in another Pakistani under the constraints of British immigration control. In one small sample, 92% of transnational marriages were with either first or second cousins. A small but non-negligible proportion end in divorce because the immigrant spouse was simply using the marriage as an excuse to enter Britain. Marriages of British Pakistan women with immigrant male Pakistanis proved more problematic than with immigrant women, partly because such men do not always have the skills to support their wives. Immigrant spouses are fairly even in gender, so the motive is not simply to import income-generating males. Rather immigration is defined by kinship ties and obligations to the extended family. It seems probable that the longer a Pakistani has been in Britain, the less their likelihood of marrying a close relative. Not surprisingly, marriages to kin in Britain has also allowed some families consolidate their social position in Pakistan using the resulting income. Researcher Alison Shaw expects marriage within the biradari among British Pakistanis to continue for some time to come, especially in the landowning castes who do not wish to marry beneath them. While those who move up in status may more confidently overlook obligations to kin and marry those of equivalent class status, possibly through "arranged love marriages," the majority may not have this luxury. The rate of biradari marriages will also depend on the extent to which young adults raised in the UK continue to value meeting obligations to kin and maintaining marital ties to Pakistan.

The Netherlands

The Netherlands has also had a recent debate that has reached the level of the Prime Minister proposing a cousin marriage ban. The proposed policy is explicitly aimed at preventing "import marriages" from certain nations like Turkey and Morocco with a high rate of cousin marriage (roughly one quarter according to one study). Critics argue that such a ban would contradict Section 8 of the European Convention on Human Rights, is not based on science, and would affect more than immigrants. While some proponents argue such marriages were banned until 1970, according to Frans van Poppel of the Netherlands Interdisciplinary Demographic Institute, they are confusing cousin marriage with uncle-niece marriage.

Other regions

In the East, South Korea is especially restrictive with bans on marriage out to third cousins, with all couples having the same surname and region of origin having been prohibited from marrying until 1997. Taiwan, North Korea, and the Philippines also prohibit first-cousin marriage. It is allowed in Japan, though the incidence has declined in recent years. China has banned it since passing its 1981 Marriage Law, yet there is a conspicuous lack of data on actual cousin marriage rates there. An article in China Daily
China Daily
The China Daily is an English language daily newspaper published in the People's Republic of China.- Overview :China Daily was established in June 1981 and has the widest print circulation of any English-language newspaper in the country...

from the 1990s reported on the ban's implementation in the northeastern provience of Liaoning
Liaoning
' is a province of the People's Republic of China, located in the northeast of the country. Its one-character abbreviation is "辽" , a name taken from the Liao River that flows through the province. "Níng" means "peace"...

, along with a ban on marriage of the physically and mentally handicapped, all justified on "eugenic" grounds. Limited existing data indicates some remaining cousin marriage of types besides father's brother's daughter in many villages, with percentages usually in the lower single digits. A 2002 Time article claims that an increasing imbalance in the number of males and females is causing more cousin marriages, as "desperate" males struggle to find brides. Currently according to the Marriage Law of the People's Republic of China, "Article 7 No marriage may be contracted under any of the following circumstances: (1)if the man and the woman are lineal relatives by blood, or collateral relatives by blood up to the third degree of kinship."

Recent 2001 data for Brazil indicates a rate of cousin marriage of 1.1%, down from 4.8% in 1957. The geographic distribution is heterogeneous: in certain regions the rate is at typical European levels, but in other areas is much higher. Freire-Maia found paternal parallel cousin marriage to be the most common type of cousin marriage. In his 1957 study the rate varied from 1.8% in the south to 8.4% in the northeast, where it increased moving inward from the coast, and was higher in rural regions than in urban. Consanguinity has decreased over time and particularly since the 19th century. For example, in São Paulo in the mid-19th century the rate of cousin marriage apparently was 16%, but a century later it was merely 1.9%.

Social aspects

Robin Bennett, a University of Washington
University of Washington
University of Washington is a public research university, founded in 1861 in Seattle, Washington, United States. The UW is the largest university in the Northwest and the oldest public university on the West Coast. The university has three campuses, with its largest campus in the University...

 researcher who led a major NSGC study on cousin marriage, has said that much hostility towards married cousins constitutes discrimination
Discrimination
Discrimination is the prejudicial treatment of an individual based on their membership in a certain group or category. It involves the actual behaviors towards groups such as excluding or restricting members of one group from opportunities that are available to another group. The term began to be...

. "It's a form of discrimination that nobody talks about. People worry about not getting health insurance — but saying that someone shouldn't marry based on how they're related, when there's no known harm, to me is a form of discrimination." But in a different view, William Saletan of Slate magazine accuses the authors of this study of suffering from the "congenital liberal conceit that science solves all moral questions." While readily conceding that banning cousin marriage cannot be justified on genetic grounds, Saletan asks rhetorically whether it would be acceptable to legalize uncle-niece marriage or "hard-core incest" between siblings and then let genetic screening take care of the resulting problems.

A recent New York Times article by Sarah Kershaw documents fear by many married cousins of being treated with derision and contempt. "While many people have a story about a secret cousin crush or kiss, most Americans find the idea of cousins marrying and having children disturbing or even repulsive," notes the article. It gives the example of one mother, Mrs. Spring, whose daughter Kimberly Spring-Winters, 29, married her cousin Shane Winters, 37. She stated that when she has told people about her daughter's marriage they have been shocked and that consequently she is afraid to mention it. They live in a small Pennsylvania town and she worries that her grandchildren will be treated as outcasts and ridiculed due to their parental status. Another cousin couple stated that their children's maternal grandparents have never met their two grandchildren because the grandparents severed contact out of disapproval for the couple's marriage. This couple withheld their names from publication.

It appears that in most societies cousin marriage is more common among those of low socioeconomic status, among the illiterate and uneducated, and in rural areas. This may be due in part to the token or significantly reduced dowries and bridewealths that exist in such marriages. But some societies also report a high prevalence among land-owning families and the ruling elite: here the relevant consideration is thought to be keeping the family estate intact over generations. There is also a lower average age at marriage for cousin marriages, the difference in one Pakistani study being 1.10 and 0.84 years for first and second cousins respectively. In Pakistan the ages of the spouses were also closer together, the age difference declining from 6.5 years for unrelated couples to 4.5 years for first cousins. A marginal increase in time to first birth, from 1.6 years generally to 1.9 years in first cousins, may occur due to the younger age at marriage of consanguineous mothers and resultant adolescent subfertility or delayed consummation.

Predictions that cousin marriage would decline during the late 20th century in areas where it is preferential appear to have been largely incorrect. One reason for this is that in many regions cousin marriage is not merely a cultural tradition but is also judged to offer significant social and economic benefits. In South Asia
South Asia
South Asia, also known as Southern Asia, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities , also includes the adjoining countries to the west and the east...

, rising demands for dowry
Dowry
A dowry is the money, goods, or estate that a woman brings forth to the marriage. It contrasts with bride price, which is paid to the bride's parents, and dower, which is property settled on the bride herself by the groom at the time of marriage. The same culture may simultaneously practice both...

 payments have caused dire economic hardship and have been linked to "dowry deaths" in a number of North India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

n states. Where permissible, marriage to a close relative is hence regarded as a more economically feasible choice. Second, improvements in public health have led to decreased death rates and increased family sizes, making it easier to find a relative to marry if that is the preferred choice. Increases in cousin marriage in the West may also occur as a result of immigration from Asia and Africa. In the short term some observers have concluded that the only new forces that could discourage such unions are government bans like the one China enacted in 1981. In the longer term it is thought that rates may decline due to decreased family sizes, making it more difficult to find cousins to marry.

Cousin marriage is important in several anthropological theories by prominent authors such as Claude Lévi-Strauss
Claude Lévi-Strauss
Claude Lévi-Strauss was a French anthropologist and ethnologist, and has been called, along with James George Frazer, the "father of modern anthropology"....

, Sir Edward Tylor, and Henry Lewis Morgan. Lévi-Strauss viewed cross-cousin marriage as a form of exogamy
Exogamy
Exogamy is a social arrangement where marriage is allowed only outside of a social group. The social groups define the scope and extent of exogamy, and the rules and enforcement mechanisms that ensure its continuity. In social studies, exogamy is viewed as a combination of two related aspects:...

 in the context of a unilineal descent group, meaning either matrilineal or patrilineal descent. Matrilateral
Matrilateral
The term Matrilateral describes kin 'on the mother's side'.Social anthropologists have underlined that even where a social group demonstrates a strong emphasis on one or other line of inheritance , relatives who fall outside this unilineal grouping will not simply be ignored...

 cross-cousin marriage in societies with matrilineal descent meant that a male married into the family his mother's brother, building an alliance
Alliance theory
The Alliance Theory is the name given to the structural method of studying kinship relations. It finds its origins in Claude Lévi-Strauss's Elementary Structures of Kinship , and is opposed to the functionalist theory of Radcliffe-Brown...

 between the two families. However, marriage to a mother's sister daughter (a parallel cousin) would be endogamous, here meaning inside the same descent group, and would therefore fail to build alliances between different groups. Correspondingly, in societies like China with patrilineal descent, marriage to a father's brother's daughter would fail at alliance building. And in societies with both types of descent, where a person belongs to the group of his mother's mother and father's father but not mother's father or father's mother, only cross-cousin marriages would successfully build alliances.

Lévi-Strauss postulated that cross-cousin marriage had the two consequences of setting up classes which automatically delimit the group of possible spouses and of determining a relationship that can decide whether a prospective spouse is to be desired or excluded. Whereas in other kinship systems one or another of these aspects dominates, in cross-cousin marriage they overlap and cumulate their effects. It differs from incest prohibitions in that the latter employs a series of negative relationships, saying whom one cannot marry, while cross-cousin marriage employs positive relationships, saying whom should marry. Most crucially, cross-cousin marriage is the only type of preferential union that can function normally and exclusively and still give every man and woman the chance to marry a cross-cousin. Unlike other systems such as the levirate, the sororate, or uncle-niece marriage, cross-cousin marriage is preferential because for obvious reasons these others cannot constitute the exclusive or even preponderant rule of marriage in any group. Cross-cousin marriage divides members of the same generation into two approximately equal groups, those of cross-cousins and "siblings" that include real siblings and parallel cousins. Consequently cross-cousin marriage can be a normal form of marriage in a society, but the other systems above can only be privileged forms. This makes cross-cousin marriage exceptionally important.

Cross-cousin marriage also establishes a division between prescribed and prohibited relatives who, from the viewpoint of biological proximity, are strictly interchangeable. Lévi-Strauss thought that this proved that the origin of the incest prohibition is purely social and not biological. Cross-cousin marriage in effect allowed the anthropologist to control for biological degree by studying a situation where the degree of prohibited and prescribed spouses were equal. In understanding why two relatives of the same biological degree would be treated so differently, Lévi-Strauss wrote, it would be possible to understand not only the principle of cross-cousin marriage but of the incest prohibition itself. For Lévi-Strauss cross-cousin marriage was not either socially arbitrary or a secondary consequence of other institutions like dual organization or the practice of exogamy. Instead, the raison d'etre of cross-cousin marriage could be found within the institution itself. Of the three types of institution of exogamy rules, dual organization, and cross-cousin marriage, the last was most significant, making the analysis of this form of marriage the crucial test for any theory of marriage prohibitions.

Matrilateral cross-cousin marriage has been found by some anthropological researchers to be correlated with patripotestal jural authority, meaning rights or obligations of the father. According to some theories, in these kinship systems a man marries his matrilateral cross-cousin due to associating her with his nurturant mother. Due to this association, possibly reinforced by personal interaction with a specific cousin, he may become "fond" of her, rendering the relationship "sentimentally appropriate." Interestingly, patrilateral cross-cousin marriage is the rarest of all types of cousin marriage, and there is some question as to whether it even exists.

In contrast to Lévi-Strauss who viewed the exchange of women under matrilateral cross-cousin marriage as fundamentally egalitarian, anthropologist Edmund Leach
Edmund Leach
Sir Edmund Ronald Leach was a British social anthropologist of whom it has been said:"It is no exaggeration to say that in sheer versatility, originality, and range of writing he was and still is difficult to match among the anthropologists of the English speaking world".-Personal and academic...

 held that such systems by nature created groups of junior and senior status and were part of the political structure of society. Under Leach's model, in systems where this form of marriage segregates descent groups into wife-givers and wife-takers, the social status of the two categories also cannot be determined by a priori arguments. Groups like the Kachin exhibiting matrilateral cross-cousin marriage do not exchange women in circular structures; where such structures do exist they are unstable. Moreover, the exchanging groups are not major segments of the society, but rather local descent groups from the same or closely neighboring communities. Lévi-Strauss held that women were always exchanged for some "prestation" which could either be other women or labor and material goods. Leach agreed but added that prestations could also take the form of intangible assets like "prestige" or "status" that might belong to either wife-givers or wife-takers.

Anthropologists Robert Murphy
Robert Murphy
Robert Murphy or Bob Murphy is the name of:In sports:*Irish Bob Murphy , American light heavyweight boxer*Bob Murphy , American sports announcer...

 and Leonard Kasdan describe preferential parallel cousin marriage as leading to social fission, in the sense that "feud and fission are not at all dysfunctional factors but are necessary to the persistence and viability of Bedoin society." Their thesis is the converse of Fredrik Barth
Fredrik Barth
Thomas Fredrik Weybye Barth is a Norwegian social anthropologist who has published several ethnographic books with a clear formalistic view...

's, who describes the fission as leading to the cousin marriage." Per Murphy and Kasdan, the Arab system of parallel cousin marriage works against the creation of homogenous "bounded" and "corporate" kin groups and instead creates arrangements where every person is related by blood to a wide variety of people, with the degree of relationship falling off gradually as opposed to suddenly. Instead of corporate units, Arab
Arab
Arab people, also known as Arabs , are a panethnicity primarily living in the Arab world, which is located in Western Asia and North Africa. They are identified as such on one or more of genealogical, linguistic, or cultural grounds, with tribal affiliations, and intra-tribal relationships playing...

 society is described as having "agnatic sections," a kind of repeating fractal structure in which authority is normally weak at all levels but capable of being activated at the required level in times of war. They relate this to an old Arab proverb: "Myself against my brother; my brother and I against my cousin; my cousin, my brother and I against the outsider." In such a society even the presence of a limited amount of cross-cousin marriage will not break the isolation of the kin group, for first cross cousins often end up being second parallel cousins." Instead of organizing horizontally through affinal ties, when large scale organization is necessary it is accomplished vertically, by reckoning distance from shared ancestors. This practice is said to possess advantages such as resilience and adaptability in the face of adversity.

In an essay published for The American Conservative, Steve Sailer
Steve Sailer
Steven Ernest Sailer is an American journalist and movie critic for The American Conservative, a blogger, a VDARE.com columnist, and a former correspondent for UPI. He writes about race relations, gender issues, politics, immigration, IQ, genetics, movies, and sports.-Personal life:Sailer grew up...

 has claimed that high rates of cousin marriage play an important role in discouraging political democracy
Democracy
Democracy is generally defined as a form of government in which all adult citizens have an equal say in the decisions that affect their lives. Ideally, this includes equal participation in the proposal, development and passage of legislation into law...

. Sailer believes that because families practicing cousin marriage are more related to one another than otherwise, their feelings of family loyalty tend to be unusually intense, fostering nepotism
Nepotism
Nepotism is favoritism granted to relatives regardless of merit. The word nepotism is from the Latin word nepos, nepotis , from which modern Romanian nepot and Italian nipote, "nephew" or "grandchild" are also descended....

.

Judaism and Christianity

Cousins are not included in the lists of prohibited relatives provided in the Bible
Bible
The Bible refers to any one of the collections of the primary religious texts of Judaism and Christianity. There is no common version of the Bible, as the individual books , their contents and their order vary among denominations...

, specifically in the books of Leviticus
Leviticus
The Book of Leviticus is the third book of the Hebrew Bible, and the third of five books of the Torah ....

 and Deuteronomy
Deuteronomy
The Book of Deuteronomy is the fifth book of the Hebrew Bible, and of the Jewish Torah/Pentateuch...

. The Old Testament
Old Testament
The Old Testament, of which Christians hold different views, is a Christian term for the religious writings of ancient Israel held sacred and inspired by Christians which overlaps with the 24-book canon of the Masoretic Text of Judaism...

 also contains several examples of married cousins. Two of the most famous are prominent in Genesis. Isaac
Isaac
Isaac as described in the Hebrew Bible, was the only son Abraham had with his wife Sarah, and was the father of Jacob and Esau. Isaac was one of the three patriarchs of the Israelites...

 was married to Rebekah, his first cousin once removed (Genesis 24:12–15). Also, Rachel
Rachel
Rachel , as described in the Hebrew Bible, is a prophet and the favorite wife of Jacob, one of the three Biblical Patriarchs, and mother of Joseph and Benjamin. She was the daughter of Laban and the younger sister of Leah, Jacob's first wife...

 and Leah
Leah
Leah , as described in the Hebrew Bible, is the first of the two concurrent wives of the Hebrew patriarch Jacob and mother of six of sons whose descendants became the Twelve Tribes of Israel, along with at least one daughter, Dinah. She is the daughter of Laban and the older sister of Rachel, whom...

 were both cousins of Isaac's son Jacob
Jacob
Jacob "heel" or "leg-puller"), also later known as Israel , as described in the Hebrew Bible, the Talmud, the New Testament and the Qur'an was the third patriarch of the Hebrew people with whom God made a covenant, and ancestor of the tribes of Israel, which were named after his descendants.In the...

. Jacob loved Rachel and worked seven years for her father Laban in return for permission to marry (Genesis 28–29). Both marriages were arranged over significant distances, with the eligible women nearby implied to be displeasing to the groom's parents (Genesis 24:3, 28:1). Jacob's brother Esau
Esau
Esau , in the Hebrew Bible, is the oldest son of Isaac. He is mentioned in the Book of Genesis, and by the minor prophets, Obadiah and Malachi. The New Testament later references him in the Book of Romans and the Book of Hebrews....

 also married his cousin Mahalath
Mahalath
Mahalath was the third mentioned wife of Esau, a daughter of Ishmael and sister of Nebajoth. Esau took Mahalath from the house of Ishmael to be his wife, after seeing that his Canaanite wives displeased his father, Isaac...

, daughter of Ishmael
Ishmael
Ishmael is a figure in the Hebrew Bible and the Qur'an, and was Abraham's first born child according to Jews, Christians and Muslims. Ishmael was born of Abraham's marriage to Sarah's handmaiden Hagar...

. According to many English Bible translations, a fourth example is the five daughters of Zelophehad, who married the "sons of their father's brothers" in the later period of Moses
Moses
Moses was, according to the Hebrew Bible and Qur'an, a religious leader, lawgiver and prophet, to whom the authorship of the Torah is traditionally attributed...

, although other translations merely say "relatives." (For example, the Catholic RSV-CE and NAB
New American Bible
The New American Bible is a Catholic Bible translation first published in 1970. It had its beginnings in the Confraternity Bible, which began to be translated from the original languages in 1948....

 differ in Numbers 36:10–12.) During the apportionment of Israel following the journey out of Egypt, Caleb
Caleb
Caleb is a male given name. A character called Caleb is named in both the Bible and Quran.-Caleb:When the Hebrews came to the outskirts of Canaan, the land that had been promised to them by God, after having fled slavery in Egypt, Moses sent twelve spies into Canaan to report on what was...

 gives his daughter Achsah
Achsah
Achsah - "anklet", was Caleb ben Yefune's only daughter . She was offered in marriage to the man who would lead an attack on the city of Debir, also called Kirjath-sepher/Kirjath-sannah...

 to his brother's son Othniel according to the NAB (Joshua 15:17), though the Jewish Talmud
Talmud
The Talmud is a central text of mainstream Judaism. It takes the form of a record of rabbinic discussions pertaining to Jewish law, ethics, philosophy, customs and history....

 argues Othniel was simply Caleb's brother (Sotah 11b). The daughters of Eleazer also married the sons of Eleazer's brother Kish in the still later time of David (1 Chronicles 23:22). King Rehoboam and his wives Maacah
Maacah
Maacah is a non-gender-specific personal name used in the Bible to refer to:*A child of Abraham's brother Nachor, evidently a boy. *The wife of Machir, Manasseh's son....

 and Mahalath
Mahalath
Mahalath was the third mentioned wife of Esau, a daughter of Ishmael and sister of Nebajoth. Esau took Mahalath from the house of Ishmael to be his wife, after seeing that his Canaanite wives displeased his father, Isaac...

 were grandchildren of David (2 Chronicles 11:20). Finally, Tobias in the book of Tobit
Book of Tobit
The Book of Tobit is a book of scripture that is part of the Catholic and Orthodox biblical canon, pronounced canonical by the Council of Carthage of 397 and confirmed for Roman Catholics by the Council of Trent...

 has a right to marry Sarah because he is her nearest kinsman (Tobit 7:10), though the exact degree of their cousinship is not clear.

In Roman Catholicism, all marriages more distant than first-cousin marriages are allowed, and first-cousin marriages can be contracted with a dispensation. This was not always the case, however: the Catholic Church has gone through several phases in kinship prohibitions. At the dawn of Christianity in Roman times, marriages between first cousins were allowed. For example, Emperor Constantine, the first Christian Roman Emperor, married his children to the children of his half-brother. First and second cousin marriages were then banned at the Council of Agde in AD 506, though dispensations sometimes continued to be granted. By the 11th century, with the adoption of the so-called canon-law method of computing consanguinity, these proscriptions had been extended even to sixth cousins, including by marriage. But due to the many resulting difficulties in reckoning who was related who, they were relaxed back to third cousins at the Fourth Lateran Council in AD 1215. Pope Benedict XV reduced this to second cousins in 1917, and finally, the current law was enacted in 1983. In Catholicism, close relatives who have married unwittingly without a dispensation can receive an annulment
Annulment
Annulment is a legal procedure for declaring a marriage null and void. Unlike divorce, it is usually retroactive, meaning that an annulled marriage is considered to be invalid from the beginning almost as if it had never taken place...

.

There are several explanations for the rise of Catholic cousin marriage prohibitions after the fall of Rome. One explanation is increasing Germanic influence on church policy. G.E. Howard states, "During the period preceding the Teutonic invasion, speaking broadly, the church adhered to Roman law and custom; thereafter those of the Germans...were accepted." On the other hand it has also been argued that the bans were a reaction against local Germanic customs of kindred marriage. At least one Frankish King, Pepin the Short, apparently viewed close kin marriages among nobles as a threat to his power. Whatever the reasons, written justifications for such bans had been advanced by St. Augustine by the fifth century. "It is very reasonable and just," he wrote, "that one man should not himself sustain many relationships, but that various relationships should be distributed among several, and thus serve to bind together the greatest number in the same social interests." Taking a contrary view, Protestants writing after the Reformation tended to see the prohibitions and the dispensations needed to circumvent them as part of an undesirable church scheme to accrue wealth, or "lucre."

Since the 13th century the Catholic Church has measured consanguinity according to what is called, perhaps confusingly, the civil-law method. Under this method, the degree of relationship between lineal relatives (i.e., a man and his grandfather) is simply equal to the number of generations between them. However, the degree of relationship between collateral (non-lineal) relatives equals the number of links in the family tree from one person, up to the common ancestor, and then back to the other person. Thus brothers are related in the second degree, and first cousins in the fourth degree.

Protestant churches generally allow cousin marriage, in keeping with criticism of the Catholic system of dispensations by Martin Luther
Martin Luther
Martin Luther was a German priest, professor of theology and iconic figure of the Protestant Reformation. He strongly disputed the claim that freedom from God's punishment for sin could be purchased with money. He confronted indulgence salesman Johann Tetzel with his Ninety-Five Theses in 1517...

 and John Calvin
John Calvin
John Calvin was an influential French theologian and pastor during the Protestant Reformation. He was a principal figure in the development of the system of Christian theology later called Calvinism. Originally trained as a humanist lawyer, he broke from the Roman Catholic Church around 1530...

 during the Reformation
Protestant Reformation
The Protestant Reformation was a 16th-century split within Western Christianity initiated by Martin Luther, John Calvin and other early Protestants. The efforts of the self-described "reformers", who objected to the doctrines, rituals and ecclesiastical structure of the Roman Catholic Church, led...

. This includes most of the major US denominations, such as Baptist
Baptist
Baptists comprise a group of Christian denominations and churches that subscribe to a doctrine that baptism should be performed only for professing believers , and that it must be done by immersion...

, Pentecostal, Lutheran, Presbyterian, and Methodist. The Anglican Communion
Anglican Communion
The Anglican Communion is an international association of national and regional Anglican churches in full communion with the Church of England and specifically with its principal primate, the Archbishop of Canterbury...

 has also allowed cousin marriage since its inception during the rule of King Henry VIII
Henry VIII of England
Henry VIII was King of England from 21 April 1509 until his death. He was Lord, and later King, of Ireland, as well as continuing the nominal claim by the English monarchs to the Kingdom of France...

. According Luther and Calvin, the Catholic bans on cousin marriage were an expression of Church rather than divine law and needed to be abolished. Protestants during the Reformation struggled to interpret the Biblical proscriptions against incest
Incest
Incest is sexual intercourse between close relatives that is usually illegal in the jurisdiction where it takes place and/or is conventionally considered a taboo. The term may apply to sexual activities between: individuals of close "blood relationship"; members of the same household; step...

 in a sensible manner, a task frustrated by facts like their omission of the daughter (but inclusion of the granddaughter) as a directly prohibited relation. John Calvin thought of the Biblical list only as illustrative and that any relationship of the same or smaller degree as any listed, namely the third degree by the civil-law method, should therefore be prohibited. The Archbishop of Canterbury reached the same conclusion soon after. But in contrast to both Protestantism and Catholicism, the Eastern Orthodox Church
Eastern Orthodox Church
The Orthodox Church, officially called the Orthodox Catholic Church and commonly referred to as the Eastern Orthodox Church, is the second largest Christian denomination in the world, with an estimated 300 million adherents mainly in the countries of Belarus, Bulgaria, Cyprus, Georgia, Greece,...

 bars up to second cousins from marrying. The 1913 Catholic Encyclopedia
Catholic Encyclopedia
The Catholic Encyclopedia, also referred to as the Old Catholic Encyclopedia and the Original Catholic Encyclopedia, is an English-language encyclopedia published in the United States. The first volume appeared in March 1907 and the last three volumes appeared in 1912, followed by a master index...

refers to a theory by the Anglican bishop of Bath and Wells
Bishop of Bath and Wells
The Bishop of Bath and Wells heads the Church of England Diocese of Bath and Wells in the Province of Canterbury in England.The present diocese covers the vast majority of the county of Somerset and a small area of Dorset. The Episcopal seat is located in the Cathedral Church of Saint Andrew in...

 speculating that Mary
Mary (mother of Jesus)
Mary , commonly referred to as "Saint Mary", "Mother Mary", the "Virgin Mary", the "Blessed Virgin Mary", or "Mary, Mother of God", was a Jewish woman of Nazareth in Galilee...

 and Joseph
Saint Joseph
Saint Joseph is a figure in the Gospels, the husband of the Virgin Mary and the earthly father of Jesus Christ ....

, the mother of Jesus
Jesus
Jesus of Nazareth , commonly referred to as Jesus Christ or simply as Jesus or Christ, is the central figure of Christianity...

 and her husband, were first cousins. Jack Goody
Jack Goody
Sir John Rankine Goody is a British social anthropologist. He has been a prominent teacher at Cambridge University, he was elected Fellow of the British Academy in 1976, and he is an associate of the US National Academy of Sciences...

 describes this theory as a "legend."

Islam

The Qur'an
Qur'an
The Quran , also transliterated Qur'an, Koran, Alcoran, Qur’ān, Coran, Kuran, and al-Qur’ān, is the central religious text of Islam, which Muslims consider the verbatim word of God . It is regarded widely as the finest piece of literature in the Arabic language...

 states that marriages between first cousins are allowed. In Sura An-Nisa
An-Nisa
Sura An-Nisa is the fourth chapter of the Qur'an, with 176 verses. It is a Medinan sura...

 (4:22–24), Allah mentioned the women who are forbidden for marriage: to quote the Qu'ran, "… Lawful to you are all beyond those mentioned, so that you may seek them with your wealth in honest wedlock…" In Sura Al-Ahzab
Al-Ahzab
Surat Al-Ahzab is the 33rd sura of the Qur'an with 73 ayat.Verse 5: Adoption in Islam.Ayat 6 contains a reference to the term Mother of Believers.Ayat 25 contains a reference to Battle of the trench....

 (33:50),
Muslims have practiced marriages between first cousins in all countries since the time of Muhammad. In many countries the most common type is between paternal cousins.

Muhammad actually did marry two relatives. One was a first cousin, Zaynab bint Jahsh
Zaynab bint Jahsh
Zaynab bint Jahsh was a wife of Muhammad and therefore a Mother of the Believers. Prior to this, she was briefly married to Muhammad's adopted son, Zayd ibn Harithah...

, who was not only the daughter of one of his father's sisters but was also divorced from a marriage with Muhammad's adopted son, Zayd ibn Haritha. It was the issue of adoption and not cousinship that caused controversy due to the opposition of pre-Islamic Arab norms. Initially Muhammad had feared to marry Zaynab because of this social disapproval, but later became convinced that the marriage was a duty imposed by revelation from the Quran (Sura Al-Ahzab 33:37).

Many of the immediate successors of Muhammad also took a cousin as one of their wives. Umar
Umar
`Umar ibn al-Khattāb c. 2 November , was a leading companion and adviser to the Islamic prophet Muhammad who later became the second Muslim Caliph after Muhammad's death....

 (R.A) married his cousin Atikah bint Zayd ibn Amr ibn Nifayl, while Ali
Ali
' |Ramaḍān]], 40 AH; approximately October 23, 598 or 600 or March 17, 599 – January 27, 661).His father's name was Abu Talib. Ali was also the cousin and son-in-law of the Islamic prophet Muhammad, and ruled over the Islamic Caliphate from 656 to 661, and was the first male convert to Islam...

 (R.A) married Fatimah
Fatimah
Fatimah was a daughter of the Islamic prophet Muhammad from his first wife Khadijah bint Khuwaylid. She is regarded by Muslims as an exemplar for men and women. She remained at her father's side through the difficulties suffered by him at the hands of the Quraysh of Mecca...

 (R.A), the daughter of his paternal first cousin Muhammad and hence his first cousin once removed.

It has been proposed that the Quranic law of inheritance through the daughter as well as the son encouraged first-cousin marriage in order to keep wealth in the family. Among Islamic societies this rule has not always been followed, but where it was, marrying a first cousin prevented familial wealth from escaping to another clan.

Hinduism

In the Mahabharata
Mahabharata
The Mahabharata is one of the two major Sanskrit epics of ancient India and Nepal, the other being the Ramayana. The epic is part of itihasa....

, one of the two great Hindu Epics, Arjuna
Arjuna
Arjuna in Indian mythology is the greatest warrior on earth and is one of the Pandavas, the heroes of the Hindu epic Mahābhārata. Arjuna, whose name means 'bright', 'shining', 'white' or 'silver' Arjuna (Devanagari: अर्जुन, Thai: อรชุน, Orachun, Tamil: Arjunan, Indonesian and Javanese: Harjuna,...

 took as his fourth wife his first and cross cousin Subhadra
Subhadra
Image:Jagannath, Baladev and Subadra in Radhadesh.jpg|thumb|right|250px|alt=|Subhadra, flanked by her brothers Balarama and Jagannatha . Deities of the Radhadesh temple in Belgium...

, the sister of Krishna
Krishna
Krishna is a central figure of Hinduism and is traditionally attributed the authorship of the Bhagavad Gita. He is the supreme Being and considered in some monotheistic traditions as an Avatar of Vishnu...

. Arjuna had gone into exile alone after having disturbed Yudhisthira
Yudhisthira
In the great Hindu epic Mahabharata, Yudhisthira , the eldest son of King Pandu and Queen Kunti, was king of Indraprastha and later of Hastinapura. He was the leader of the Pandava side in the Kurukshetra War...

 and Draupadi
Draupadi
In the epic Mahābhārata, Draupadi, also known as ' is the "emerged" daughter of King Drupada of Panchāla and the wife of the five Pandavas. When Yudhisthira becomes the king of Hastinapura at the end of the war, Draupadi becomes the queen of Indraprastha...

 in their private quarters. It was during the last part of his exile, while staying at the Dvaraka residence of his cousins, that he fell in love with Subhadra. While eating at the home of Balaramaji, Arjuna was struck with Subhadra's beauty and decided he would obtain her as his wife. Subhadra and Arjuna's son was the tragic hero Abhimanyu
Abhimanyu
Abhimanyu is a tragic hero in the Hindu epic, the Mahābhārata. He is the son of Arjuna and Subhadra, who is the half-sister of Lord Krishna...

. According to Andhra Pradesh
Andhra Pradesh
Andhra Pradesh , is one of the 28 states of India, situated on the southeastern coast of India. It is India's fourth largest state by area and fifth largest by population. Its capital and largest city by population is Hyderabad.The total GDP of Andhra Pradesh is $100 billion and is ranked third...

 oral tradition, Abhimanyu himself married his first cross-cousin Sasirekha, the daughter of Subhadra's brother Balarama
Balarama
Balarama , also known as Baladeva, Balabhadra and Halayudha, is the elder brother of the divine being, Krishna in Hinduism. Within Vaishnavism Hindu traditions Balarama is worshipped as an Avatar of Vishnu, and he is also listed as such in the Bhagavata Purana...

. Later, Abhimanyu and his other wife Uttara had a son, Parikshit, who eventually succeeded Yudhisthira as the emperor of the Pandava kingdom after Abhimanyu was killed at Kurukshetra
Kurukshetra
Kurukshetra is a land of historical and religious importance. Historically the land belonged to Punjab now a district in Haryana state of India. It is a holy place and is also known as Dharmakshetra . According to the Puranas, Kurukshetra is named after King Kuru, the ancestor of Kauravas and...

.

In Hinduism marriage within the same gotra
Gotra
In the Hindu society, the term Gotra broadly refers to people who are descendants in an unbroken male line from a common male ancestor. Panini defines gotra for grammatical purposes as apatyam pautraprabhrti gotram , which means "the word gotra denotes the progeny beginning with the son's son"...

 is prohibited, where a gotra is believed to be the group of descendants of a sage who lived in the remote past. Two persons in the same gotra cannot marry even if they come from different linguistic areas. However, same-gotra marriages have been legal under Indian civil law since the Hindu Marriage Act of 1955. Additionally, marriages within certain degrees of consanguinity
Consanguinity
Consanguinity refers to the property of being from the same kinship as another person. In that respect, consanguinity is the quality of being descended from the same ancestor as another person...

 are considered sapinda
Sapinda
Sapinda is a term used in context of cousin marriages in Hinduism.For example, if the bride is the offspring of the any person within five generations on the groom's father's side and three generations on the groom's mother's side, or vice-versa, they will be referred to as "sapindas" of each other...

 and banned in Hinduism. Hindu lawgivers differ in the definition of sapinda: at one extreme, according to some sources marriages are prohibited within seven generations on the father's side and five on the mother's side. In contrast, other sources allow cross cousins to marry, including first cross cousins. The Hindu Marriage Act bars marriage for five generations on the father's side and three on the mother's side, but allows cross-cousin marriage where it is permitted by custom.

Hindu rules of exogamy
Exogamy
Exogamy is a social arrangement where marriage is allowed only outside of a social group. The social groups define the scope and extent of exogamy, and the rules and enforcement mechanisms that ensure its continuity. In social studies, exogamy is viewed as a combination of two related aspects:...

 are often taken extremely seriously, and local village councils in India administer laws against in-gotra endogamy, . Social norms against such practices are quite strong as well.

In the 18th and 19th Centuries, Hindu
Hindu
Hindu refers to an identity associated with the philosophical, religious and cultural systems that are indigenous to the Indian subcontinent. As used in the Constitution of India, the word "Hindu" is also attributed to all persons professing any Indian religion...

 Kurmi
Kurmi
The Kurmi are a Hindu agricultural Jāti in India.The group has been associated with the Kunbi, though scholars differ as to whether the terms are synonymous. In 2006, the Indian government announced that Kurmi was considered synonymous with the Kunbi and Yellam castes in Maharashtra...

s of Chunar
Chunar
Chunar छुनर شُنَر, located in Mirzapur District of Uttar Pradesh state, India, is an ancient town. The railway tracks passing through Chunar leads to major destinations of India, including Howrah, Delhi, Tatanagar and Varanasi. National Highway number 7 also passes through Chunar...

 and Jaunpur
Jaunpur, Uttar Pradesh
Jaunpur is a city and a municipal board in Jaunpur district in the Indian state of Uttar Pradesh.Jaunpur district is located to the northwest of the district of Varanasi in the eastern part of the North Indian state of Uttar Pradesh. According to the 2001 census, Jaunpur district had a population...

 are known to have been influenced by their Muslim neighbors and taken up extensively the custom of cousin marriage.

Other religions

Buddhism
Buddhism
Buddhism is a religion and philosophy encompassing a variety of traditions, beliefs and practices, largely based on teachings attributed to Siddhartha Gautama, commonly known as the Buddha . The Buddha lived and taught in the northeastern Indian subcontinent some time between the 6th and 4th...

 does not proscribe any specific sexual practices, only ruling out "sexual misconduct" in the Five Precepts. Zoroastrianism
Zoroastrianism
Zoroastrianism is a religion and philosophy based on the teachings of prophet Zoroaster and was formerly among the world's largest religions. It was probably founded some time before the 6th century BCE in Greater Iran.In Zoroastrianism, the Creator Ahura Mazda is all good, and no evil...

 allows cousin marriages. Sikhism largely follows the pattern of ban on the same clan marriages, particularly amongst the Jatt Sikhs. On the other hand, certain Sikh families do permit cross-cousin marriages and they are valid under the Hindu Marriage Act 1955 as allowed by custom.

Genetics

Cousin marriage has genetic aspects that do not arise in the case of other marriage-related political and social issues like interracial marriage. This is because married couples possessing higher than normal consanguinity have, on average, an increased chance of sharing genes for recessive traits. Consanguinity
Consanguinity
Consanguinity refers to the property of being from the same kinship as another person. In that respect, consanguinity is the quality of being descended from the same ancestor as another person...

 means the amount of shared (identical) DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

, the genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

 material. The percentage of consanguinity between any two individuals decreases fourfold as the most recent common ancestor
Most recent common ancestor
In genetics, the most recent common ancestor of any set of organisms is the most recent individual from which all organisms in the group are directly descended...

 recedes one generation. To cite some examples, first cousins have four times the consanguinity of second cousins, while first cousins once removed have half that of first cousins. Rare double first cousins have twice that of first cousins and are as related as half-siblings.

In April 2002, the Journal of Genetic Counseling released a report which estimated the average risk of birth defects in a child born of first cousins at 1.7–2.8% over an average base risk for non-cousin couples of 3%, or about the same as that of any woman over age 40. In terms of mortality, a 1994 study found a mean excess pre-reproductive mortality rate of 4.4%, While another study published in 2009 suggests the rate may be closer to 3.5%. Put differently, first-cousin marriage entails a similar increased risk of birth defects and mortality as a woman faces when she gives birth at age 41 rather than at 30. Critics argue that banning first-cousin marriages would make as much sense as trying to ban childbearing by older women. After repeated generations of cousin marriage the actual genetic relationship between two people is closer than the most immediate relationship would suggest. In Pakistan, where there has been cousin marriage for generations and the current rate may exceed 50%, one study estimated infant mortality at 12.7 percent for married double first cousins, 7.9 percent for first cousins, 9.2 percent for first cousins once removed/double second cousins, 6.9 percent for second cousins, and 5.1 percent among nonconsanguineous progeny. Among double first cousin progeny, 41.2 percent of prereproductive deaths were associated with the expression of detrimental recessive genes, with equivalent values of 26.0, 14.9, and 8.1 percent for first cousins, first cousins once removed/double second cousins, and second cousins respectively.

Even in the absence of preferential consanguinity, alleles that are rare in large populations can randomly increase to high frequency in small groups within a few generations due to the founder effect
Founder effect
In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1942, using existing theoretical work by those such as Sewall...

 and accelerated genetic drift
Genetic drift
Genetic drift or allelic drift is the change in the frequency of a gene variant in a population due to random sampling.The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces...

 in a breeding pool of restricted size. For example because the entire Amish
Amish
The Amish , sometimes referred to as Amish Mennonites, are a group of Christian church fellowships that form a subgroup of the Mennonite churches...

 population is descended from only a few hundred 18th century German-Swiss settlers, the average coefficient of inbreeding between two random Amish is higher than between two non-Amish second cousins. First-cousin marriage is taboo among Amish but they still suffer from several rare genetic disorders. In Ohio's Geagua County, Amish make up only about 10 percent of the population but represent half the special needs cases. In one debilitating seizure disorder the worldwide total of 12 cases is exclusively Amish. Similar disorders have been found in the highly polygynous FLDS, who do allow first-cousin marriage and of whom 75 to 80 percent are related to two 1930s founders.

Studies into the effect of cousin marriage on polygenic traits and complex diseases of adulthood have often yielded contradictory results due to the rudimentary sampling strategies used. Both positive and negative associations have been reported for breast cancer and heart disease. Long-term studies conducted on the Dalmatian islands in the Adriatic Sea have indicated a positive association between inbreeding and a very wide range of common adulthood disorders, including hypertension, coronary heart disease, stroke, cancer, uni/bipolar depression, asthma, gout, peptic ulcer, and osteoporosis. However, these results may principally reflect village endogamy rather than consanguinity per se. Endogamy is marrying within a group and in this case the group was a village. The marital patterns of the Amish are also an example of endogamy.

The Latin American Collaborative Study of Congenital Malformation found an association between consanguinity and hydrocephalus, postaxial polydactyly, and bilateral oral and facial clefts. Another picture emerges from the large literature on congenital heart defects, which are conservatively estimated to have an incidence of 50/1,000 live births. A consistent positive association between consanguinity and disorders such as ventricular septal defect and atrial septal defect has been demonstrated, but both positive and negative associations with patent ductus arteriosus, atrioventricular septal defect, pulmonary atresia, and tetralogy of Fallot have been reported in different populations. Associations between consanguinity and Alzheimer's disease have been found in certain populations. Studies into the influence of inbreeding on anthropometric measurements at birth and in childhood have failed to reveal any major and consistent pattern, and only marginal declines were shown in the mean scores attained by consanguineous progeny in tests of intellectual capacity. In the latter case, it would appear that inbreeding mainly leads to greater variance in IQ levels, due in part to the expression of detrimental recessive genes in a small proportion of those tested.

A BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...

 report discussed Pakistanis in Britain
British Asian
British Asian is a term used to describe British citizens who descended from mainly South Asia, also known as South Asians in the United Kingdom...

, 55% of whom marry a first cousin. Given the high rate of such marriages, many children come from repeat generations of first-cousin marriages. The report states that these children are 13 times more likely than the general population to produce children with genetic disorder
Genetic disorder
A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions....

s, and one in ten children of first-cousin marriages in Birmingham
Birmingham
Birmingham is a city and metropolitan borough in the West Midlands of England. It is the most populous British city outside the capital London, with a population of 1,036,900 , and lies at the heart of the West Midlands conurbation, the second most populous urban area in the United Kingdom with a...

 either dies in infancy or develops a serious disability. The BBC also states that Pakistani-Britons, who account for some 3% of all births in the UK, produce "just under a third" of all British children with genetic illnesses. Published studies show that mean perinatal mortality
Perinatal mortality
Perinatal mortality , also perinatal death, refers to the death of a fetus or neonate and is the basis to calculate the perinatal mortality rate. Variations in the precise definition of the perinatal mortality exist specifically concerning the issue of inclusion or exclusion of early fetal and...

 in the Pakistani community of 15.7 per thousand significantly exceeds that in the indigenous population and all other ethnic groups in Britain. Congenital anomalies account for 41 percent of all British Pakistani infant deaths. The BBC story contained an interview with Myra Ali, whose parents and grandparents were all first cousins. She has a very rare recessive genetic condition, known as Epidermolysis bullosa
Epidermolysis bullosa
Epidermolysis bullosa is an inherited connective tissue disease causing blisters in the skin and mucosal membranes, with an incidence of 1/50,000. Its severity ranges from mild to lethal. It is caused by a mutation in the keratin or collagen gene....

 which will cause her to lead a life of extreme physical suffering, limited human contact and probably an early death from skin cancer. Knowing that cousin marriages increase the probability of recessive genetic conditions, she is understandably against the practice. Finally, in 2010 the Telegraph reported that cousin marriage among the British Pakistani community resulted in 700 children being born every year with genetic disabilities.

The increased mortality and birth defects observed among British Pakistanis may, however, have another source besides current consanguinity. This is population subdivision
Wahlund effect
In population genetics, the Wahlund effect refers to reduction of heterozygosity in a population caused by subpopulation structure. Namely, if two or more subpopulations have different allele frequencies then the overall heterozygosity is reduced, even if the subpopulations themselves are in a...

 among different Pakistani groups. Population subdivision results from decreased gene flow among different groups in a population. Because members of Pakistani biradari have married only inside these groups for generations, offspring have higher average homozygosity even for couples with no known genetic relationship. According to a statement by the UK's Human Genetics Commission
Human Genetics Commission
The Human Genetics Commission is a non-departmental public body body that advises the UK government on the ethical and social aspects of genetics...

 on cousin marriages, the BBC also "fails to clarify" that children born to these marriages were not found to be 13 times more likely to develop genetic disorders. Instead they are 13 times more likely to develop recessive genetic disorders. The HGC states, "Other types of genetic conditions, including chromosomal abnormalities, sex-linked conditions and autosomal dominant conditions are not influenced by cousin marriage." The HGC goes on to compare the biological risk between cousin marriage and increased maternal age, arguing that "Both represent complex cultural trends. Both however, also carry a biological risk. They key difference, GIG argue, is that cousin marriage is more common amongst a British minority population." Genetic effects from cousin marriage in Britain are more obvious than in a developing country like Pakistan because the number of confounding environmental diseases is lower. Increased focus on genetic disease in developing countries may eventually result from progress in eliminating environmental diseases there as well.

Comprehensive genetic education and premarital genetic counseling programs can help to lessen the burden of genetic diseases in endogamous communities. Genetic education programs directed as high school students have been successful in Middle Eastern countries such as Bahrain
Bahrain
' , officially the Kingdom of Bahrain , is a small island state near the western shores of the Persian Gulf. It is ruled by the Al Khalifa royal family. The population in 2010 stood at 1,214,705, including 235,108 non-nationals. Formerly an emirate, Bahrain was declared a kingdom in 2002.Bahrain is...

. Genetic counseling in developing countries has been hampered, however, by lack of trained staff, and couples may refuse prenatal diagnosis and selective abortion despite the endorsement of religious authorities. In Britain, the Human Genetics Commission recommends a strategy comparable with previous strategies in dealing with increased maternal age, notably as this age relates to an increased risk of Down Syndrome. All pregnant women in Britain are offered a screening test from the socialized medical system to identify those at an increased risk of having a baby with Down syndrome. The HGC states that similarly, it is appropriate to offer genetic counseling to consanguineous couples, preferably before they conceive, in order to establish the precise risk of a genetic abnormality in offspring. Under this system the offering of genetic counseling can be refused, unlike for example in the US state of Maine where it is mandatory to marry. Leading researcher Alan Bittles also concluded that though consanguinity clearly has a significant effect on childhood mortality and genetic disease in areas where it is common, it is "essential that the levels of expressed genetic defect be kept in perspective, and to realize that the outcome of consanguineous marriages is not subject to assessment solely in terms of comparative medical audit." He states that the social, cultural, and economic benefits of cousin marriage need to also be fully considered.

Fertility

Higher total fertility rates are reported for cousin marriages than average, a phenomenon noted as far back as George Darwin during the late 19th century. There is no significant difference in the number of surviving children in cousin marriages because this compensates for the observed increase in child mortality. The total fertility increase may be partly explained by the lower average parental age at marriage, and age at first birth, observed in consanguineous marriages. Other factors include shorter birth intervals and possibly a lower likelihood of using reliable contraception. There is also the possibility of more births as a compensation for increased child mortality, either via a conscious decision by parents to achieve a set family size or the cessation of lactational amenorrhea following the death of an infant. According to a recent paper the fertility difference is probably not due to any underlying biological effect. In Iceland where marriage between second and third cousins were common in part due to limited selection studies show higher fertility rates Third Cousins Have Greatest Number Of Offspring, Data From Iceland Shows Earlier papers have claimed that increased sharing of human leukocyte antigen
Human leukocyte antigen
The human leukocyte antigen system is the name of the major histocompatibility complex in humans. The super locus contains a large number of genes related to immune system function in humans. This group of genes resides on chromosome 6, and encodes cell-surface antigen-presenting proteins and...

s, as well as of deleterious recessive genes expressed during pregnancy, may lead to lower rates of conception and higher rates of miscarriage in consanguineous couples. Others now believe there is scant evidence for this unless the genes are operating very early in the pregnancy. Studies consistently show a lower rate of primary infertility in cousin marriages, usually interpreted as being due to greater immunological compatibility between spouses.

Famous cousin marriages

Famous cousin marriages in the United States include Edgar Allan Poe
Edgar Allan Poe
Edgar Allan Poe was an American author, poet, editor and literary critic, considered part of the American Romantic Movement. Best known for his tales of mystery and the macabre, Poe was one of the earliest American practitioners of the short story and is considered the inventor of the detective...

, Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

, Franklin Delano Roosevelt, and Jerry Lee Lewis
Jerry Lee Lewis
Jerry Lee Lewis is an American rock and roll and country music singer-songwriter and pianist. An early pioneer of rock and roll music, Lewis's career faltered after he married his young cousin, and he afterwards made a career extension to country and western music. He is known by the nickname 'The...

.

In Latin America, famous figures who married their cousin include prominent author and 2010 Nobel Prize
Nobel Prize
The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...

 laureate Mario Vargas Llosa
Mario Vargas Llosa
Jorge Mario Pedro Vargas Llosa, 1st Marquis of Vargas Llosa is a Peruvian-Spanish writer, politician, journalist, essayist, and Nobel Prize laureate. Vargas Llosa is one of Latin America's most significant novelists and essayists, and one of the leading authors of his generation...

, and former Peruvian beauty queen Marina Mora
Marina Mora
Marina Mora Montero was Miss Peru 2002 and represented Peru in Miss World 2002. She finished as 2nd runner up.-Personal life:Marina has been married once. In 2005, she married her first cousin, Gustavo Mora. They later separated.-References:...

.

See also

  • Affinity (canon law)
    Affinity (canon law)
    In Canon law of the Catholic Church, affinity is a relationship which "arises from a valid marriage, even if not consummated, and exists between a man and the blood relatives of the woman and between the woman and the blood relatives of the man."...

  • Cousin marriage in the Middle East
    Cousin marriage in the Middle East
    Cousin marriage is at least allowed throughout the Middle East. Anthropologists have debated the significance of the practice; some view it as the defining feature of the Middle Eastern kinship system while others note that overall rates of cousin marriage have varied sharply between different...

  • Cousin marriage in the United States
  • Cousin marriage law in the United States by state
  • Endogamy
    Endogamy
    Endogamy is the practice of marrying within a specific ethnic group, class, or social group, rejecting others on such basis as being unsuitable for marriage or other close personal relationships. A Greek Orthodox Christian endogamist, for example, would require that a marriage be only with another...

  • Genetic sexual attraction
    Genetic sexual attraction
    Genetic sexual attraction is a term that describes the phenomenon of sexual attraction between close relatives, such as siblings, first and second cousins or a parent and offspring, who first meet as adults.- History and definition :...

  • Jewish views on incest
  • Mahram
    Mahram
    In Islamic sharia legal terminology, a mahram is an unmarriageable kin with whom sexual intercourse would be considered incestuous, a punishable taboo...

  • Pedigree collapse
    Pedigree collapse
    In genealogy, pedigree collapse describes how reproduction between two individuals who knowingly or unknowingly share an ancestor causes the number of distinct ancestors in the family tree of their offspring to be smaller than it could otherwise be. Robert C...

  • Westermarck effect
    Westermarck effect
    The Westermarck effect, or reverse sexual imprinting, is a hypothetical psychological effect through which people who live in close domestic proximity during the first few years of their lives become desensitized to later sexual attraction. This phenomenon was first hypothesized by Finnish...


External links

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