what determines the childs looks?

[Compass]

both parents have natural hair colors and walk normally, but the child came out with blue ends (hair) and walking angrily

[Ani Blade]

Is the colour swatch just what that hair looks like? Because genetics pull from the hair they have on (assuming CC works the same). There are some hairs where half or most are dyed. If it's only partly coloured, the swatch sometimes shows the actual hair colour instead. The kid might still have a plausible variant.
As for walk style, it seems really weird for that to be genetic and not randomly generated given that it's "personality" based and nothing medical, etc

[CrackeR]

Facial structure and breast size seem to be inherited from the mother, ie; mother has high basketball breasts then daughter will have em also, if mom has big saggy funbags then daughter will as well, same with small breasts.
Hair color in my experience is nearly always the same as parents , but those hairs with the same base color, with tinted ends can result as well.

[Exploatores]

I got a large save. when it comes to parents. In my experience. if you got a parent with black hair and the other is blond. the hair color is going to be eather parents or between the parents. same for eyes and skin. the tint comes from hairstyle and those are random.

[Jehane]

Originally posted by Exploatores:

I got a large save. when it comes to parents. In my experience. if you got a parent with black hair and the other is blond. the hair color is going to be eather parents or between the parents. same for eyes and skin. the tint comes from hairstyle and those are random.

Pretty much. One of my Sims couples has five kids; the dad has brown hair, the mom light blonde hair. Two of their kids have brown hair, or used to because one of them changed it to green, the other three have blond hair. The oldest daughter also has the mother's grey eyes, and I think the second daughter does, too. I haven't checked with the other kids yet, but I bet their eyes are either green or grey.

[PandoraWolfCrow]

don't worry ! be happy ! EA works groups come from Wokism XD so....XD

[Sovereign Dark]

It's generally a mess if you're not using mods to control genetic inheritance percentages. Most versions of the game have been this way, though. Kids grow up looking ... questionable.

I just use cas.fulleditmode cheat and adjust child/teen appearances to achieve the best genetic accuracy. Full edit requires testing cheats are enabled to use. < testingcheats true

Edit: If using the method, then Shift+click on the sim for the cheats menu and choose Modify in CAS.