The whole 'they don't look like the parents' thing is especially annoying. I mean, sure, it can have many reasons, but the chances that an entire neighborhood adopted kids just don't seem that big. xD And it happens so often, I spend quite a lot of time correcting it. Then again, this isn't just the case for townies for me. When my toddlers grow up, they often have an entirely different hair/eye color that came completely out of nowhere, too. Or they're born with an entirely different skin color than the parents to begin with (although I have to admit the last time this happened was a long time ago, I'm not sure if that has been fixed by now). It just all seems very random to me.
