a recessive trait might stay hidden for many generations. let us use the child from the last example. we will call her "mary". mary has brown hair but has genes for both red and brown hair. let us say mary grew up and married tom. tom also has brown hair, but like mary one of his parents had red hair. this means tom has genes for both red and brown hair. mary and tom would each have a chance of passing either brown or red hair genes to their children. this means that the children of mary and tom could have either red or brown hair. this explains why a person might look different from their parents, but look like their grandparents or great-grandparents.