How can He have dark brown hair if his parents had medium brown and blonde hair?

My grandmother has blonde hair. My grandfather has a medium chestnut brown. However, their son has a very very very dark brown head of hair. How can this be? By the rules of Mendalin inheritance, how can this combo of parents produce this hair?

How can He have dark brown hair if his parents had medium brown and blonde hair?
Things like hair color and skin tone are controlled by more than one gene. They are not that classic dominant/recessive trait. They are called polygenic traits. So the result of any cross is not going to give you a median trait. Its not like mixing paint. Two parents with black hair can have a red-haired offspring. It would be unusual, but it is not impossible.





No more dark thoughts about G'ma and G'pa's love life/faithfulness!!!
Reply:may the ur grandparents will having a recessive allele of dark brown hair which would have caused it


since both would have it in them


it would got active in their son





grandmom has active blonde hair genes


granddad has active medium chestnut brown genes
Reply:there must be a cracker in the wood pile
Reply:Look deep in the family tree. It's all in the family genes.