Well, I don't know about your kids, but one of mine was born with a full head of almost black (my colour) hair, about 3 inches long. So I see nothing unusual about this. My other daughter was born with no hair, and had none till she was a year old. She now has the most wonderful, multi-coloured thick, lustrous hair.
http://news.bbc.co.uk/1/hi/england/d...re/6972359.stm