<P> Cousin marriage was legal in all states before the Civil War . Anthropologist Martin Ottenheimer argues that marriage prohibitions were introduced to maintain the social order, uphold religious morality, and safeguard the creation of fit offspring . Writers such as Noah Webster (1758--1843) and ministers like Philip Milledoler (1775--1852) 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 (1818--1881) was writing about "the advantages of marriages between unrelated persons" and the necessity of avoiding "the evils of consanguine marriage", avoidance of which would "increase the vigor of the stock". To many, Morgan included, cousin marriage, and more specifically parallel - cousin marriage, was a remnant of a more primitive stage of human social organization . Morgan himself had married his cousin in 1853 . </P> <P> In 1846, Massachusetts Governor George N. Briggs appointed a commission to study mentally handicapped people (termed "idiots") in the state . This study implicated cousin marriage as responsible for idiocy . Within the next two decades, numerous reports (e.g., one from the Kentucky Deaf and Dumb Asylum) appeared with similar conclusions: that cousin marriage sometimes resulted in deafness, blindness, and idiocy . Perhaps most important was the report of physician Samuel Merrifield Bemiss for the American Medical Association, which concluded cousin inbreeding does lead to the "physical and mental depravation of the offspring". Despite being contradicted by other studies like those of George Darwin and Alan Huth in England and Robert Newman in New York, the report's conclusions were widely accepted . </P> <P> These developments led to 13 states and territories passing cousin marriage prohibitions by the 1880s . Though contemporaneous, the eugenics movement did not play much of a direct role in the bans . George Louis Arner in 1908 considered the ban a clumsy and ineffective method of eugenics, which he thought would eventually be replaced by more refined techniques . By the 1920s, the number of bans had doubled . Since that time, Kentucky (1943) and Texas have banned first - cousin marriage and since 1985, Maine has mandated genetic counseling for marrying cousins to minimise risk to any of serious health defect to their children . The National Conference of Commissioners on Uniform State Laws unanimously recommended in 1970 that all such laws should be repealed, but no state has dropped its prohibition . </P> <P> Early Medieval Europe continued the late Roman ban on cousin marriage; under the law of the Catholic Church, couples were forbidden to marry if they were within four degrees of consanguinity . In the ninth century, the church raised the number of prohibited degrees to seven and changed the method by which they were calculated . Eventually, the nobility became too interrelated to marry easily as the local pool of unrelated prospective spouses became smaller; increasingly, large payments to the church were required for exemptions ("dispensations"), or retrospective legitimizations of children, in what amounted to a' protection racket' by the church . In 1215, the Fourth Lateran Council reduced the number of prohibited degrees of consanguinity from seven to four . The method of calculating prohibited degrees was changed also . Instead of the former practice of counting up to the common ancestor then down to the proposed spouse, the new law computed consanguinity by counting back to the common ancestor . In the Roman Catholic Church, unknowingly marrying a closely consanguineous blood relative was grounds for a declaration of nullity, but during the 11th and 12th centuries, dispensations were granted with increasing frequency due to the thousands of persons encompassed in the prohibition at seven degrees and the hardships this posed for finding potential spouses . After 1215, the general rule was that while fourth cousins could marry without dispensation, the need for dispensations was reduced . </P>

When did it become illegal to marry first cousins
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