i quite agree with Katie. by the simple law of genetics, one of them is bound to have hermione's hair colour , or somewhere near her colour at least . her chocolate - brown eyes also might belong to one of her parents, but it is not always the case .
Well, one of her parents would have to have light brown or dirty blonde hair, for starters. Also, at least one of them would have to have her colour eyes (I think they're brown, but don't quote me on that).
Hermione's average height, it seems, so her parents would probably be somewhere around her stature.
umm..... if Hermione did wipe out her parent's memories, then it wouldn't make a difference to them whether or not she told them about it , would it? also, hermione was in tears in the burrow.
I can't picture Hermione Charming her parents' memory without telling them what she was going to do beforehand -- it just seems, i dunno, cruel to do that. And also, she planned it so that she'd be removing the Charms when this was all over, so she must've thought about the possible reactions her parents would have, i.e., 'How do we know this was the only time you've done that?' and such.