I've always stayed clean-shaven.* Partly because on some level I want to distinguish myself from my dad's full beard, but also a tendency to dislike itch and that the light color would make me look odd. Remember that's just what I suspect, not having firsthand evidence. :|
*OTOH, I tend to shave once a day in the evenings, and so have perma-Clint Eastwood stubble most days.
I have one younger brother with a civil-war style goatee, another with tendencies toward soul patches, and a third who's in the greasy teen laziness phase.
Someday I may go beardish, but not today. And kids? ZZ Top style efforts take ~8 years, according to Billy Gibbons.