Sour Grapes
Of course we're Fair and Balanced!

2004-10-18

The American Myth of Cousin Marriage



This is the subtitle of a 1996 book written by Martin Ottenheimer, in which he dissects this supposed myth. The always highly readable and entertaining Cecil Adams took this topic up recently in one of his columns called The Straight Dope:



  • The U.S. is virtually alone among developed nations in outlawing marriage among first cousins. European countries have no such prohibition. In some cultures, particularly Islamic ones, first-cousin marriage is encouraged....
  • A recent review (Bennett et al, Journal of Genetic Counseling, 2002) says that, on average, offspring of first-cousin unions have a 2 to 3 percent greater risk of birth defects than the general population, and a little over 4 percent greater risk of early death. While those margins aren't trivial, genetic testing and counseling can minimize the danger. An argument can be made that marriages of first cousins descended from strong stock can produce exceptional children....
  • [T]he formerly high incidence of congenital defects, specifically hemophilia, among European royal families isn't the classic demonstration of the perils of inbreeding that everybody thinks it is. The short explanation is that hemophilia is an X-chromosome-related characteristic, transmitted only through the female line. The children of royal female carriers would have been at risk no matter whom their mothers had married.



I've long wondered how intermarriage could have been avoided through most of human history. Up until very recently — at least in terms of the whole span of Homo sapiens' existence — it was extremely uncommon for people to travel more than a few miles from where they were born. Maybe it wasn't!



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