Even Britain, which has afforded Muslims a more welcoming environment, has had some worrying moments. A few years back, a Labor M.P. called for an end to “the tradition of first-cousin marriages” among Pakistanis and other South Asians in Britain. The basis for her suggestion was the claim that Pakistanis in Britain were more likely than the general population to suffer from recessive autosomal genetic disorders. Of course, so are Ashkenazi Jews, but you can hardly imagine an M.P. proposing to limit Jews’ marriage choices for this reason, especially given the historic Nazi allegation of Jewish genetic inferiority.

Noah Feldman