Sims mobile genetics - my family tree

So I've been playing the game for some time now and I was wondering how genetics work, so I conducted a little research by myself and this are my conclusions; I haven't experienced and weird glitches with hair colour, eye colour or skin colour, everything worked normal in that regard, although I haven't been playing daily for a few months now, so perhaps one of the later patches broke that and I've just been lucky so far. All the descendants appear to only inherit looks from parents and looks of the grandparents appear to be irrelevant. I also didn't experience any random mutations, children were usually just a combination of parent's looks. I didn't experience children inheriting body shapes but perhaps that is my fault because I wasn't looking very closely and I didn't make sims with really specific body shapes in first place.

So here is my family tree so far. I positioned pictures similarly to have they are on the sims 4 thread about genetics. Parent that is the descendant of the family is always on the far left and parent that was a game created townie is on the far right, not all partners were townies but I will mention it separately where that was the case. The pictures of the children were taken in the cas when they aged up to young adults and I made them playable.
First generation:

Both parents were created by me.
Second generation:

Third generation:


at this point I wanted to have a baby girl so I choose an option to adopt a girl and discovered she doesn't share any physical resemblance with her parents which is not such a surprise. The other daughter was a biological child, her dad had cyan hair before he aged up to senior.
Fourth generation:

So yeah this relationship is slightly icky because their parents were a brother and a sister but the game seems to not really care about it. I justified it with the fact that he moved out before she was even born and the fact that they weren't really blood related but it's still a bit icky :D

Fifth generation:

Her husband was not game created but was made by me. I just couldn't find any male young adults in my game that I liked at the time.

This son baffles me the most, I have no idea from where he picked up the ears or the nose or the face shape. I did notice that when for example son inherits mom's looks they appear pretty different, but if the son than has a daughter that inherits his looks they appear the same as they were on her grandmother.

Let me just say that I've played sims on pc quite extensively a few years ago but I've never reached fifth generation (sims 3 really had a bit of a problem with save files corrupting I've always ended my family with the blue screen), I really like this aspect of the game.