Skin Tones NEED an update. Genetics NEED fixing

Sometimes my sim children have the same skin color as one of the parents, but sometimes they have a skin color that's somewhere in between the two.

It could have something to do with the warm, cool, and neutral palettes. If one parent is warm dark and another is cool light, there's a pretty wide variety of possibilities. But if both parents are on the warm palette, it's more likely to be somewhere in the middle. That's my guess anyways.