You're only as old as your behaviour on the 'net.
It's funny, I always associate beards with "old" people. Realise it's something from my childhood, but I still assumed Spamray is "really old" (tm) due to the bearded avatars he uses. Now I discover we're both "in our 30's".
IMO, age is a factor, but it's maturity that matters. Of course the older you are, the more you know (generally speaking) and the less likely you are to be naive, ignorant or immature. In most cases, dealing with a young person who is mature is fine, unless their lack of experience affects things.