Talk:List of Minor Characters in The Tailor of Enbizaka/@comment-14601489-20160727080040/@comment-27496045-20160727134833

In real life hair genetics can be complicated so this is a very simple explanation.

If there is at least one grandparent from each side of the family tree had blond hair or blond hair genes, then they could pass those genes onto Ren's parents. Blond hair is a recessive trait, so it is only expressed if there aren't any dominant hair genes like brown and black. So, Kayo would need to have a black hair gene and a blond hair gene, and Gakuga would need to have a blond hair gene and a "purple hair" gene. Baby Ren would get one gene from both parents and if those genes were both for blond hair then he would be blond.