How about we hit this old style, with a quiz question:

Tell me, what relates a man (we will just refer to him as 'he') to four people with a different hair colour.

First right answer gets psychonauts.

Just for men!

He is related to them by the simple fact that they are all men.

They all have hair. ;p

it's really not something you would guess, the clue is more in the original statement of why...

he's the dad

"He" is bald...

Look back guys.

A black haired man is related to his father who now has gray hair. He related to his grandfather who now has white hair. He is related to his brother who inherited a recessive gene for blond hair from both his parents and he is related to his son who inherited a dominant trait for brown hair.

if Momo1991 isn't right, I'm going to guess that it is all the same person after having different hair colours.

Um, had to take Biology over again for my late-in-life college do over!

They're all human, and thus closely related?

He's the lead singer of Kajagoogoo during one song.

Psychonauts?

I heard they re-formed, sporting many tatoos.

though You're not right.