Comprehensive genetic education and premarital genetic counseling programs can help reduce the burden of genetic disease in endogamous communities. Genetic education programs for high school students have been successful in Middle Eastern countries such as Bahrain. However, genetic counseling in developing countries has been hampered by a lack of trained personnel, and couples may refuse prenatal diagnosis and selective abortion despite support from religious authorities.  In the United Kingdom, the Commission for Human Genetics recommends a strategy comparable to previous strategies for dealing with increasing maternal age, especially since this age is associated with an increased risk of Down syndrome. All pregnant women in the UK are offered a screening test by the National Health Service to identify those who are at increased risk of having a baby with Down syndrome. The HGC notes that it is also appropriate to offer genetic counseling to pairs of relatives through blood, preferably before conception, to determine the exact risk of genetic abnormality in offspring. Under this system, the offer of genetic counseling can be denied, unlike, for example, the state of Maine, where genetic counseling is required to obtain a marriage license for first-degree cousins. Lead researcher Alan Bittles also concluded that while inbreeding clearly has a significant impact on infant mortality and genetic diseases in areas where it is common, it is “important that the extent of the expressed genetic defect is put into perspective and recognizes that the outcome of consanguineous marriages is not only evaluated for comparative medical audits.”  He notes that the social, cultural and economic benefits of marriage between cousins must also be fully considered.  Shaw and Saller, in their thesis on low rates of marriage between cousins, suggest that when families from different regions were incorporated into the imperial Roman nobility, exogamy was necessary to accommodate them and not to destabilize the Roman social structure. Their data on tombstones further suggest that in most of the Western Empire, marriages between cousins were not widespread, even among citizens. Spain and Noricum were exceptions to this rule, but even there the rates did not exceed 10%.
 They further point out that, since the assets of the nobility were generally fragmented, there was no advantage in keeping current assets in the family over acquiring them through mixed marriages. Jack Goody argued that early Christian marriage rules force a marked departure from previous norms to deny heirs to the rich, increasing the chances that those with wealth will leave their property to church. However, Shaw and Saller believe that the estates of aristocrats without heirs had already been claimed by the emperor and that the church simply replaced the emperor. They believe that Christian injunctions against cousin marriage were due more to ideology than to a conscious desire to acquire wealth.  Some states only allow marriages with first-degree cousins if the couple cannot have children because they are too old or if one of the parties is deemed barren. A cousin marriage is a marriage in which the spouses are cousins (that is, people with common grandparents or people who share other ancestors at a relatively young age). The practice was common in the past and is still common in some societies today, although in some jurisdictions such marriages are prohibited.  Worldwide, more than 10% of marriages take place between first cousins or second cousins.  Marriage between cousins is an important topic in anthropology and covenant theory.
 The Puritans, the Quaker tradition, and the Roman Catholic Church have traditionally opposed marriages between first cousins. First cousins can marry without restriction in nineteen U.S. states, mostly on the East Coast. Some famous historical figures married their cousins. Outlaw Jesse James married his first cousin Zerelda. Scientist Albert Einstein married his second-degree cousin Elsa. And several presidents have married cousins of more distant relatives. The Yoruba are 50% Muslim, 40% Christian and 10% followers of their own indigenous religious traditions.  A 1974 study analyzed Yoruba marriages in the town of Oka Akoko and found that among a sample of highly polygamous marriages with an average of about three women, 51% of all couples were related by blood. This included not only marriages between cousins, but also uncle-niece ties.
According to some reports, it is customary for at least one of the spouses in such marriages to be a parent and, in general, these spouses were the preferred or preferred wives in the marriage and gave birth to other children. However, this was not a general study of the Yoruba, but only of the highly polygamous Yoruba living in Oka Akoko.  Data on cousin marriages in the United States are scarce. It was estimated in 1960 that 0.2% of all marriages between Catholics took place between first cousins or second cousins, but no recent national studies have been conducted.  It is not known what proportion of this number was first cousin, that is, the group facing marriage prohibitions. To contextualize the group size, the total proportion of interracial marriages in 1960, the last census year before the end of the anti-miscegenation laws, was 0.4%, and the proportion of black and white marriages was 0.13%.  While recent studies cast serious doubt on whether marriage between cousins is as dangerous as is generally believed, Professors Diane B. Paul and Hamish G.
Spencer have speculated that legal prohibitions persist in part because of the “ease with which a handful of highly motivated activists—or even an individual—can be effective in the decentralized American system. especially if the feelings on the other side of a problem are not high.”  Utah allows first-degree cousins to marry only if both parties are 65 years of age or older, or if both are 55 years of age or older, with a district court finding that one or both parties are infertile. First cousins from Utah are not allowed to live together or have sex. However, first cousins who have been abducted once can marry. So what happens when what the heart wants is generally considered taboo? Many may raise eyebrows at the thought of marrying their cousin, but the practice has long been considered common for those who had holed up in communities over several generations. Like Maryland, Massachusetts allows first-degree cousins, first cousins once removed, to marry half-cousins by adoption, live together, and have sex. You may be surprised to learn that most Western European countries have no restrictions on marriages between first cousins. Predictions that marriage between cousins would decline in regions where it is favored in the late 20th century appear to have been largely wrong.
One reason for this is that, in many areas, marriage between cousins is not only a cultural tradition, but also offers significant social and economic benefits. In South Asia, the growing demand for dowry payments has led to severe economic hardship and has been linked to “dowry-related deaths” in a number of northern Indian states. To the extent permitted, marriage to a close relative is therefore considered a more economically feasible choice. Second, improvements in public health have led to lower mortality rates and increased family size, making it easier to find a parent who can marry when it is the preferred choice. An increase in cousin marriages 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 China`s in 1981. In the longer term, rates could decline due to smaller family sizes, making it harder to find cousins to marry.  In Texas, a marriage is void if one party to the marriage is related to the other, including first-degree cousins. In 2012, a married couple in India was unable to provide a notice from the Texas attorney general stating that such marriages are legal in Texas, as requested by U.S. immigration officials. Their failure to have their marriage recognized by the state underscores the differences in public policy between conservative and less conservative states.
For many families, marriage offers the opportunity to classify immigrants as spouses. To qualify for classification, the marriage must be a legal marriage under U.S. immigration laws. In most cases, the law of the place of celebration is governed by the Foreign Affairs Manual (MAF). That is, if the marriage was legally valid in the foreign jurisdiction in which it was contracted, the marriage is considered valid for visa decisions in the United States. The U.S. state of Maine allows marriage to a first-degree cousin if the couple accepts genetic counseling, while North Carolina allows it as long as the marriage candidates are not rare first-degree double cousins, that is, cousins of both parental lines.  In the other 25 states that allow at least some marriages with first cousins, there is no distinction between double cousins.  The rules for first cousins who have been expelled once are somewhat lax, as they and half-cousins are allowed to marry by adoption.