From my understanding, the only kinds of traits that will not be passed down generations are the odd ones like blue hair and skin, only natural colors are able to be passed down for some reason (there is a mod for this: simscommunity info/social/threads/unnatural-hair-colours-are-now-genetic-child-hairs-recoloured 260/). With facial features, they are passed down, but it is random from the two sims. So, if one of your sims has eyes that are close together there is a chance that the child will also have eyes that are close together.
