Both my parents had dark hair, three out of four of my grandparents too, the other, my grandfather on my fathers side was a redhead when younger but darker colored as I remember him.
I have noticed a tinge of red in many beards, including my father and brother. Both had black hair that turned red as it went into their beards but black again toward the chin. Later the black portions turned grey but the red stayed red for a while, until it too greyed out.
When younger I had bright red hair.
As I got older it darkened to brown.
Older still and part of it turned grey, the other part went elsewhere (landfill, birds nests, etc)
Same with the beard.
Now the pubic hair, that is another story; for another time.