¹¹Of course, one might argue that the ‘dynasty’ of the childless couples could be carried on by nephews and nieces, or second cousins, or any other heir who might be found. However, such an argument only intensifies the problems with the dynastic model pointed out by Bagwell and Bernheim 1988, to wit, that sexual reproduction and non-perfectly-assortative mating imply that eventually one’s own descendants are so intermixed with everyone else’s that there is no plausible sense in which a ‘dynasty’ can be said to exist at all.