So, a few weeks ago, my wife and I visited her parents. When we arrived, a very handsome man walked by with his dog. My wife started talking with him as if they had known each other all their lives. Well, when I was finally properly introduced, it turned out that they really did know each other almost all their lives. The man, as it turned out, grew up with my wife and they used to play together as kids around the neighborhood.
For some reason, his name escapes me at this moment. What I do know is he is a graduate of an ivy league school. Smart, physically fit, handsome, friendly to animals, very liberal views, etc., basically every woman's dream man.
After the guy went on to continue walking his dog, I jokingly asked my wife why she didn't marry him, and her answer was "ewww, it's like marrying my brother". Later that day, I asked the in-law and her answer was basically the same.
Intrigued by both of their answers, I'd since asked a dozen other females and they all gave the same answer. I asked them if they'd date and marry a man who they grew up with in the neighborhood if he was the perfect man of their dream, and they all gave me the same "ewww, that's nasty" answer.
Have I stumbled upon an biological instinct in females to diversify the gene pool by having an instinctual negative reaction to mating a male that's near by? After all, inbreeding, even beyond the family but within a group or clan, would inevitably result in a not-so diversified gene pool.
Thoughts, biologists?
Creationist views are also welcomed.