In the late 19th century, George Darwin, a child of first-cousin parents, investigated the parental consanguinity of inmates of lunatic asylums in England. He found the prevalence of cousin marriage among the parents of inmates to be no higher than among the general population, and so could “only draw the negative conclusion that as far as insanity and idiocy go, no evil has been shown to accrue from consanguineous marriages”1(p1434) [italics in original]. But, he added, “it might still be shown, by more accurate methods of research, that it is so.”1(p1436)