>>63
Given my interest in both genetics and psychology, you'd think someone would have told me about this. Now, I'm no biologist, but here's how I see it:

People are attracted to attractive people. You know, individuals who have features that reflect being healthy and fertile, who lack physical deviations from the norm, and who have whatever other indicators it is that either sex seeks in the other. In other words, what people are after is the genotype that leads to a (likely to be) evolutionarily-successful phenotype.

Genetic similarity doesn't seem to have much to do with it. Unattractive people who end up together seem to do so more out of social pressure than otherwise. Everyone wants the hottie. Nor does it explain sexual attraction between members who come from populations that are likely to be significantly different.