There has been some discussion in the comments why the posts on inbreeding are getting so much attention. I think this is a milder form of the same sort of curiosity about why young males have a fascination with pornography: we are obsessed with sex. This is not an arbitrary fascination, nor is it a loss of innocence which may have been avoided. Sex is our raison d’etre as sexual organisms. Evolutionary psychology gets a bad reputation for positing adaptive explanations for everything under the sun, from dancing to migraines. But, if there is anything which is the target of adaptive constraint and selective pressures, it is the suite of traits which relate to sex and mating in a direction fashion. It is sometimes stated that sex is about power, but the bigger reality is that power is about sex.
But reducing human behavior purely to one explanatory framework is too reductive even for me. An individualist framework where singular males and females operate as evolutionary versions of rational H. economicus, always optimizing fitness through subterfuge and inducement, leaves something to be desired in characterizing the true rich …