Well, blonde plus blonde usually equals blonde. And if one parent is blonde but the other isn't, there is a chance the kid will be blonde too. And I think (although I can't prove it) the grandparents, great-grandparents and so on can contribute to a child's looks as well. Like, a black-haired child could have two blonde parents but one of its grandparents had black hair. Again, I can't prove that one. Someone who has more experience with villager genetics may be better able to help.