The 'grey hair' connection is an interesting one. I can't verify this at all but interesingly many members of my family have a genetic disposition to a grey or white streak of hair. I've have had a distinct white patch in my hair since birth
Interesting but possibly muddying the waters as I suspect this genetic tendency is more my mother's side of the family (Barnes)
This genetic tendency was also made famous by local North Eastern UK writer Catherine Cookson in the Mallens.
The Mallen Streak " All Thomas Mallen's sons had inherited his distinctive flash of white hair, known as the Mallen Streak, and it was said that nothing good ever came of a Mallen. In 1851, Thomas Mallen found himself a ruined man, forced, amid scandal and disgrace, to sell High Banks Hall and adjust to a new way of living. "
Hmmm Maybe Cathering Cookson knew a thing or two more about the Reay's