This is my sons hair! He is 8-months-old. He was born with very little but dark hair. When he was about a month old it…

This is my sons hair! He is 8-months-old. He was born with very little but dark hair. When he was about a month old it all fell out and since then I have seen tiny blond hairs, ... although, the dark brown hair grew in lightly. It is currently patchy, and its as if he has 2 layers- the under layer is very light bright blond but there is a brown hair layer over it. In pictures he appears blonde, I’m just wondering why it is taking so long for his hair to define itself? Anyone else experience anything similar to this??!