@mw1525 - Also in fairness I am not showing the other parent, who also has distinctive features, in that post. The younger two sons on the left were teens when those shots were taken, the daughter and oldest son on the right were YAs. True enough about the oldest son's buzzed haircut, but I think we can see enough of the ears on the other three to see that they did not happen to pick up the same particular genetic element (slider values) from that parent and they are each either 0 or from the other side of the family. :)
Edit: Unless, maybe it's your point that the features on the younger two will evolve more when they get older? I believe I checked that and it didn't happen, but would have to go back to that save from ages ago to make sure. This wasn't my real game, it was a total "what if" off to the side. In my real game the two sims are busy running a huge farm together with a sibling and sibling-in-law and none of them have any kids yet.