[Jeff the Green]

Originally Posted by noparlpf

So I really don't understand how the attraction to people similar to one's parents thing worked out evolutionarily, I would have expected it to work out like the what's-his-name thing if I had been theorising this stuff while studying primates a few hundred thousand years back. Slight tangent now, looks likes.

Tangent:

Spoiler

Because some inbreeding is good. While sibling relationships have a greatly increased risk of genetic disease, cousin relationships don't have a significantly increased risk (for most populations) and have fewer fertility issues. The closer a woman is related to her partner, the less likely her body will attack the sperm on its way to the ovum.