[hablog]

Yeah, for an illustrative example of assortative mating effects, consider the stereotype of the rich nerd with the hot wife. Kids are smart and attractive. This plays out at every pareto level in the sexual marketplace.

Basically, monogamy breaks the ability of sexual selection to "dilute" bad genes with good ones. I'm not anti-monogamy, but it's a social technology which has tradeoffs (this being one of them).