system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why aren't people attracted to family members?
gpt
I mean they can be, incest is a thing. But if you want an evolutionary explanation, incest can often lead to severe birth defects in children and as a result, it is evolutionarily beneficial to have a hardwired response to avoid that. And that is likely what happened (I say likely because all current evidence seems to be anecdotal).