User blog comment:WayfinderOwl/Questions about sims children/@comment-27606819-20130122210208

I read something about the red hair gene being dominant over blonde and I think this true. A very easy tester is the child of Loki and Circe Beaker. The father is blonde, mother is red; most of the time the child turns out to be a redhead. I think in later generations (lets say the third or maybe fourth one) it's also a little easier to 'avoid' the dominant genes. This just has to do with luck, as a Sim might show black hair but also has the blonde gene and the other Sim has brown hair and also the blonde gene. They both might just pass on the blonde gene and create a blonde child, even though both of the parents don't show the blonde hair. That this rarely happens is true, but I think it's not impossible.