I've noticed Genetics play on my sim's looks, and it's never for the better.
My poor Sim's son Cory got his mother's squinty eyes and his father's high cheek bones, so he looks perpetually miserable, and like a girl.
His poor sister's worse off though, she somehow got the nose of Shrek, but the sad-face-ness too.
The genetics would be interesting if people inherited the 'fat' gene, since there's conditions like that in life. I've also gotten the most gorgeous hair colors from the kids of my sims. They're usually beautiful browns or dark blonde colors. I should take a few screen shots of 'em.