Probably for a good reason -- or rather, several.
Visiting -- or even just viewing photos of family members -- prompts brain activity that affects how you feel about them, your friends, and even yourself, a new study suggests.
"We like to be around people that look more like us, but we do not find them as sexually attractive," added Platek, editor-in-chief of the journal Frontiers in Evolutionary Neuroscience. "I think it is linked to our subconscious ability to detect facial resemblances so we avoid lusting after those that may be related to us."
The scientists found that relatives and self-lookalikes are processed through a self-referential part of the brain. Friends and strangers who look nothing like the viewer, on the other hand, light up entirely different areas of the brain, those linked to making important and risky decisions with respect to the self.
Since relatives are processed through areas of the brain linked to self-reference, the study could also help to explain why relatives cause us to take things personally.
Yet another consequence of multiculturalism:
When people who really aren't like you at all are introduced to a society, suddenly everyone vaguely like you starts to seem like a relation. So you head for whatever isn't already you.
This research explains inherent in-group/out-group human tendencies: we group by evolutionary paths, with those who look similar having passed similar tests and thus having similar abilities, thus allowing us to breed for those traits.
However, when society truly becomes a random mix of people, that collapses, and we start averaging ourselves.