My sister has 4 boys, ages 21 down through 15....3 of them can grown facial hair if they choose....my sister and I both encourage their girlfriend to NOT kiss them until they shave! Teasing, of course, it's their own business whether they do so or not!
Of course, bil didn't have so much as a shadow until he was close to thirty, so it's also a great opportunity to torment HIM over his sons being more "manly" lol....