I can't remember my mother not having salt-and-pepper coloured hair, more salt when she died at 40. My younger sister had jet black hair as a child and it was almost white by the time she was 20 - probably a genetic trait.
I think my hair (blond child gradually turning to dark brown by my second pregnancy) started showing some white in my 40s, and now is probably more grey than brown in my 70s.
Pictures of my Dad in his 30 show him almost bald on top, and with just a rim of grey hair around the sides and back by his death at 56. Seelerman's hair was thinning by 40 and is very thin on top now, and our son is balder than his father.
Who knows what colour Seelergirl's hair might be. She was blond, but she started highlights as a young adult. I suspected it darkened with time, but she still prefers blond so we might never know if there is some grey or white in there.