Children won't inherit their parents nose/mouth (bug in genetics)

They don't inherit the mouth either, not just the nose. That's important.

I've had this bug in my game for years now, both with noses and lips. It's as if the children didn't inherit the parents' "size" and "width" sliders. Very weird.

I reported something similar 3 months ago it's probably related. However it is Archived.
I did the same thing I made two identical parents using the last face preset in CAS and made a child of the same age. Surprise surprise several of the features aren't inherited properly. (Old GIF, but the results are still the same in the newest update so I didn't bother to make a new GIF to show the same thing.)
Modified Facial Features aren't Inherited | EA Forums - 11723500 

It's an ooooold bug and reported years ago. I really hope that it will get fixed. 

Same thing happens to me except worse. Their faces sometimes even come out distorted where they have no chin like their heads are scrunched together. Or giant eyes and noses. Sometimes their features are so overly exaggerated they come out bugged. Genetics simply just don’t work. They come out looking monstrous compared to their parents.

I think genetics in general are bugged. 

But the child should not be a clone of his parents. He is similar, but a little different. Do you want identical clones? Another issue is that the size of the nose, eyes and ears should not only increase as a result of the genetic difference.

A little randomization is fine, but that's not the case here. Because every single one of their children looks like this. They ALWAYS have exactly the same wide nose and exactly the same upside-down mouth. They NEVER inherit the narrow nose or the mouth that curves upwards in the centre. And yes, when I have a couple, I want people to recognise their parents in their children. And in this case, in my opinion, you don't. Because the nose is completely different and so is the mouth.

He should be a clone of his parents as that's how genetics in this game is supposed to work, if you take two sims who are identical and give them a child, the child should be identical to the parents. The fact this happens instead is a bug. Naturally, the only way to easily discover this bug is by using identical parents to easily pin point which features aren't being passed down correctly.