Incest

[SteveDallas]

Originally Posted by HungLikeJesus

Incest among animals is very common, so I would say that our reaction is learned.

I don't doubt there's a lot of truth in that. But it seems like a tendency to inbreed would be undesirable from an evolutionary standpoint... in the long run wouldn't those who went out and mixed up the gene pool win out? So I would think there is some biological basis to it.