I used to think YES of course. But now I'm not so sure....?
My 86 year old Papa has a grey beard, but the hair on his head is blonde.
My 52 year old brother is a dark blonde, and not one grey hair.
My late Mama was 59 when she passed away, and not one grey hair. Her hair was a mouse-y light brown.
I'm 48 and haven't seen a grey hair yet. Am I going to go grey? I hope I do. I want short white hair at some point.