Short explanation of the words used below for familial relations.
Raphael Patai reports that in central Arabia no relaxation of a man's right to the father's brother's 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 ibn 'amm but she cannot marry another unless he gives consent. Among the Jews of Yemen this rule is also followed albeit not as rigidly. In northern Arabia the custom is very strong and any outsider wishing to marry a girl must first come to the ibn 'amm, ask his permission, and pay him what he wants, and a man who marries his daughter without the consent of the ibn 'amm risks his life. The right of the ibn 'amm is so strong that even a powerful shaykh may not be able to prevail against it. Among the Bedouin it can even happen that a ibn 'amm can lodge a complaint after the marriage has taken place, compelling the father to give up the bride price or have the marriage annulled. If he cannot marry the girl immediately due to financial or other considerations, the ibn 'amm can also "reserve" her by making a public and formal statement of his intentions to marry her at a future date. It can also happen that a more distant relative acquires priority to marry a girl over her ibn 'amm by reserving her soon after her birth. But if the girl is in love with another man and the cousin gives up his right to marry her, this is considered a noble deed and worthy of commemoration.
In one case in Jordan, a 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. The Catholic Bedouin of Jordan are also known to respect this right. In traditional Palestine, if a girl had no ibn 'amm or he renounced his right to her, the next in line was traditionally the ibn khal, or mother's brother's son, who in turn was followed by other cousins and the brother of her sister's husband, each having a right proportional to his degree of relationship. But Patai's observations in 1947 showed that among middle class Palestinians this right was on the decline, although it remained in force among the more conservative rural population.
In Syria the right belongs to the ibn 'amm alone and the ibn khal has no special rights. The custom is however less frequent in big cities such as Damascus and Aleppo. Patai reports that in the decades preceding 1962 the right was often ignored among the Syrian urban middle class. Among the upper classes it appeared to be again more common, as certain leading families protected their wealth and status by reserving daughters for their cousins, though sons had more freedom of choice. This situation was also loosening at the time of Patai's work. This holds also among the Syrian Turks and Kurds. But the Syrian Circassians hold cousin marriage absolutely forbidden, similar to the Circassians of the Caucasus.
In her discussion of the city of Aleppo during the Ottoman Empire, Meriwether finds a rate of cousin marriage among the elite of 24%. Father's brother's daughter was most common but still only represented 38% of all cousin marriages, while 62% were with first or second cousins. But most families had either no cousin marriages or only one, while for a few the rate was as high as 70%. Cousin marriage rates were higher among women, merchant families, and older well-established families. Meriwether cites one case of cousin marriage increasing in a prominent family as it consolidated its position and forging new alliances became less critical. Marriage patterns among the elite were, however, always diverse and cousin marriage was only one option of many. Rates were probably lower among the general population.
In Iraq the right of the cousin has also traditionally been followed. The Uncle of the girl -or father of the boy- assigns or reserves his niece to his son at an early age, the parents from both families arrange for the marriage usually early. This is usually done to preserve wealth in the family and is more common in rural areas. Among the Jews of Iraq, if the cousin cannot be persuaded to forgo his rights, then he is paid a sum of money by the girl's father. Among the Kurdish Hamawand tribe the ibn 'amm must give his consent for the marriage to take place, though in the southern Kurdish regions the cousin right is not as strongly emphasized. In Persian Azerbaijan and among Arabs and Berbers in Morocco the cousin right has also traditionally prevailed.
In Egypt cousin marriage may have been even more prevalent than in Arabia in past periods, with one source from the 1830s observing that it was common among Egyptian Arabs but less so in Cairo than in other parts of Egypt. Reportedly the husband and wife would continue to call each other "cousin" because the tie of blood was seen as indissoluble while the marriage was not. In the upper and middle classes the young man was seldom allowed to see the face of his female cousin after she reached puberty. Cousin marriage was not only common among Muslims but also among Egyptian Copts in the past although to a small extent not exceeding 7% of all Coptic marriages. Estimates from the late 19th and early 20th century state variously that either 80 percent of the Egyptian fellahin marry first cousins or two-thirds marry them if they exist. Cousin marriage was also practiced in the Sinai Peninsula, where a girl is sometimes reserved by her cousin with money long before puberty, and among Bedouins in the desert between the Nile and the Red Sea. In-marriage was less frequent in the late pre-Islamic Hijaz than in ancient Egypt, where during the late Roman Republic it not only included cousin marriage but also, in one of the exceptional cases of history, full sibling marriage. Cousin marriage was practiced in Medina during Muhammad's time, but out of 113 recorded marriages in one sample only 15 were between abnaa 'amm or paternal cousins of any degree.
Cousin marriage is common among the Kababish tribe of the Sudan.
Cousin marriage was practiced in ancient Persia as well as modern Iran. The Achaemenid kings habitually married their cousins and nieces. In a more recent example, in October 1867 the Crown Prince of Persia was married his cousin at age sixteen. The percentage of Iranian cousin marriages increased from 34% to 44% between the 1940s and 1970s, according to one study. There is a strong preference for marrying a first cousin, but no specific preference for the father's brother's daughter. For the quarter of women married after age 21 it was found that the incidence of consanguinity declined. Additionally, the proportion of cousin marriage among urban families stayed constant: it was only rural families that drove the increase. For all periods the proportion of cousin marriage among highly educated women was somewhat lower than among uneducated women. It is hypothesized that decreases in infant mortality during the period may have created a larger pool of eligible cousins to marry.
Barth finds in his study of southern Kurdistan that in tribal villages 57% of all marriages were cousin marriages (48% bint 'amm marriages) while in a nontribal village made up of recent immigrant families only 17% were cousin marriages (13% bint 'amm). In the South Palestinian village of Artas in the 1920s, of 264 marriages 35, or 13.3%, were ibn 'amm marriages; 69, or 26.1%, were cousin marriages. In the oasis-village of Sidi Khaled, some 170 miles south of Algiers, among the Mzabites further south, among the Chaamba, and among the Moors of the extreme western Sahara, cousin marriage is preferred. In the town of Timbuctoo, a field investigator found that among the Arabs one third of marriages are with first cousins. Half of these are with the father's brother's daughter and slightly fewer with the mother's brother's daughter. It is possible that the high MBD marriage rate is the result of Songhoi influence, one group of which prefers the MBD type and shuns the FBD type, and another group of which have a preference for both. The third ethnic group of Timbuctoo are the Bela, who are Tuareg slaves, and among whom marriage between cross cousins is preferred in principle, though in practice FBD marriage also occurs. In Lebanon first-cousin marriage rates differs among religious groups as it is found to be 17% for Christians and 30% for Muslims throughout the past century, however first-cousin marriage is declining among all marriages in Lebanon.
Patai states in his other book The Myth of the Jewish Race that percentage of cousin marriage among Jews varies extensively with geographic location. Among Israeli Ashkenazi Jews, who originate mainly from Europe, the first-cousin marriage rate was measured in a 1955-7 study at 1.4% and other cousin marriages at 1.06% of all marriages. But among non-Ashkenazim the first-cousin marriage rate was 8.8% and an additional 6.0% of marriages were between more distant cousins. Thus a total 14.6% of marriages between non-Askenazim were consanguineous compared with only 2.5% for Ashkenazim. The highest frequencies of cousin marriages were found among Jews from Iraq (28.7%) and Iran (26.3%). High rates were also found among couples from Yemen (18.3%), Aden (17.8%), Tunisia (13.4%), and among Oriental Jews from the USSR (6.9%). Jews from Egypt, Syria, Lebanon, and Turkey saw rates of 7-10.7%. A later 1969-70 study rated the first-cousin marriage rate among Ashkenazim at 0.3% and other cousin marriages at 1.0%, while for non-Askenazim the respective figures were 6.2% and 8.1%. Among the Habbani Jews in Israel, 56% of marriages are between first cousins. The Samaritans also had very high rates of inbreeding, with 43% of marriages between first cousins and 33.3% between other cousins.
Of particular significance in this region is marriage to a father's brother's daughter. Many Middle Eastern peoples express a preference for this form of marriage. Ladislav Holý explains that it is not an independent phenomenon but merely one expression of a wider preference for agnatic solidarity, or solidarity with one's father's lineage. Due to placing emphasis on the male line, the daughter of the father's brother is seen as the closest marriageable relation. 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." Along with an aversion to hypogamy that prevents the loss of a man's loyalties to the higher ranking relatives of his wife, FBD marriage more closely binds the agnatic group by ensuring that wives are agnatic as well as affinal relatives. In fact cousin marriage in general can be seen as trading off one socially valuable outcome, namely marital alliances with outsiders and the resulting integration of society, with the alternative outcome of greater group solidarity. But for demographic reasons the ideal of in-marriage can never be fully realized and hence societies allowing it can always draw on the advantageous aspects of both in- and out-marriage.
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. Both this and the emphasis of agnatic solidarity have been reinforced by the spread of Islam, though they were not created by it. The Quran mentions the greater importance of men than women (2:228, 4:34) and insists on inequality in matters such as inheritance (Quran 4:11), divorce (2:272) and legal standing (2:282). But the conceptualization of gender relations whereby men are charged with the control of and responsibility for women is not traceable to either the Quran or the hadiths: it is rather the product of numerous exegeses of Quranic texts by medieval scholars. There is in fact no actual Islamic belief in female inferiority beyond the cited excerpts.
The notion of honor is another social characteristic Holy identifies as being related to Middle Eastern cousin marriage. The honor of the males surrounding a woman is sullied in many societies when she misbehaves or when she is attacked. In societies like Europe that place greater value on affinal relations, responsibility for a married woman rests with both her husband's family and her own. In the Middle East the situation is different in that primary responsibility continues to rest with the woman's own family even after she is married. Her agnates therefore cannot release her from control upon marriage due to the risk to their honor. They and not the husband may be responsible for killing her, or sometimes her lover, if she commits adultery. Similar rules may apply in case of the payment if she is killed and for the inheritance of her property if she has no male heirs. Her natal family may continue supporting her even against her husband. This is an idealized system: some Middle Eastern societies do mix it with other systems that assign more responsibility to the husband's family.
Holy's field experience among the Berti of the Pakistan allowed him to undertake an extensive study of cousin marriage in their culture. Holy believed that many of his findings could generalize to other Middle Eastern groups. He noted that stated reasons for cousin marriage could be both pragmatic and symbolic. Stated pragmatic reasons for cousin marriage might be stated in terms of advantages for the husband such as warmer relations with his father-in-law, quicker entertainment of the husband's family by the wife in the case of a visit due to them being her relations, greater loyalty and devotion of the wife, and the ease of regaining a wife after a serious quarrel where she has withdrawn to the house of her own family. Stated pragmatic reasons for the parents included gaining access to the labor of a daughter's children by marrying her to a kinsman and thereby keeping her family close by, increased attentiveness on the part of a wife to her aging in-laws if she is related to them, and the ease of marital negotiations if the parents are brothers, or in the next best case, if the mother of one child is the sister of the father of the other child.
Holy states that despite all this, creating a general theory of the existence of a preference for FBD marriage in terms of pragmatic reasons is not possible. Instead any realistic theory must take into account the symbolic reasons that both are created by and help to create Berti culture. Frequently such reasons protected the symbolic but vitally important honor of the stakeholders involved. One reason was that in Berti (and Middle Eastern) culture one's honor is affected if a cousin becomes pregnant out of wedlock. The responsibility to see her married is directly proportional to the responsibility for her chastity and one's genealogical distance from her. One can eliminate this directly by becoming her husband. Another reason is the relationship between cousin marriage and agnatic solidarity. Holy argues from the case of the Palestinians that FBD marriage should not be viewed as simply "adding" affinal ties to previous agnatic ones. Instead they recognize the strength of the existing ties. Distant agnates can increase their bond and become close agnates via intermarriage.
The Persian king Ardesher advised his lawyers, secretaries, officers, and husbandmen to "marry near relatives for the sympathy of kinship is kept alive thereby." The same motivation is given in ancient Arabic sources referring to the practice of marriage between paternal cousins prevalent in pre-Islamic Arabia. The Kitab al-Aghani similarly features the story of Qays ibn Dharih, who was not allowed by his father to marry a beautiful maiden from another tribe because, in the words of the father felt that as rich and wealthy man he did not want his son to take the side of a stranger. There is the related consideration that a man who grows up with a cousin in the intimate setting of one extended family knows her and so may develop his own liking or love for her. There is also the benefit of knowing the qualities of the spouse: a Syrian proverb reads, "Ill luck which you know is better than good luck with which you get acquainted." Keeping property in the family is a final reason for cousin marriage. One of the earliest examples of this is the five daughters of Zelophehad from ancient Israel (Numbers 36) who upon inheriting from their father all married their father's brother's sons. The Quranic law dictating that daughters receive a portion of the inheritance appears to have had the effect of increasing cousin marriage rate.
Advice on cousin marriage in the Middle East has not always been positive, however. al-Maydani makes the following exhortation: "Marry the distant, but not the near." The reason given for the advisability of cousin marriages is most frequently the belief that the offspring of such marriages will be feeble. An early Arab author, Ibn 'Abd Rabbihi, states in his work Kitab al-'iqd al-farid of a hero that "He is a hero not borne by the cousin (of his father), he is not weakly; for the seed of relations brings forth feeble fruit." Abu Hamid al-Ghazali (1059–1111) in his principal ethical work, the Ihya 'ulum al-din, gives the different reason that "the woman should not be a near relative of the husband, because near relationship diminishes the sensuous desire." Finally the ancient Arabic poet 'Amr b. Kulthum states, "Do not marry in your own family, for domestic enmity arises therefrom." Similar sentiments are expressed by certain Moroccan and Syrian proverbs.
Patai summarizes the Middle Eastern situation by saying that a preference for ibn 'amm marriage exists in many Middle Eastern ethnic groups but that right to the bint 'amm exists in only some of these. The cousin right is the "complete" form of the institution of the cousin marriage and preference without right the "incomplete" form. Patai explains the differences between cultures exhibiting these two forms in terms of the geographic centrality to Middle Eastern culture, with groups on the outskirts of the Middle East likely to fall into the "incomplete" category, in terms of the cultural marginality of the group, with groups adhering tightly to older traditions better able to resist the "complete" form, in terms of modernization and Westernation, with this tending to discourage cousin marriage. The Copts of Egypt are described as exhibiting the "incomplete" form because of their cultural marginality, while many large Middle Eastern cities exhibit it due to their Westernization.
Cousin marriage normally results in a reduced bride price. Patai states that bride price to a cousin is usually about half as high as to a nonrelative. Due to the poverty of many families this outlay often requires exceptional effort, and especially because the decision traditionally is in the hands of the groom's father, these considerations may weigh heavily on the outcome. The bride's family moreover is expected to spend much of the bride price on the bride herself, so there is a reduced incentive to gain a higher price by avoiding 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.
Marriage between first cousins doubles the risk of children being born with birth defects, according to a study seeking answers to the higher than expected rates of deaths and congenital abnormalities in babies born from such marriages.
Dr Muhammad Ali, a District Health Officer (DHO) at Charsadda's district hospital, says that first-cousin marriages result in children with genetic disorders. "Birth defects due to inter-family marriages is not just prevalent in Mian Kalay; this can happen anywhere in the world where there is inbreeding."