I actually AM already "old" ( 36 ) and only started.
Don't get me wrong, I "knew" D&D. I had friends in high school who played it. And I myself actually played a VERY LITTLE BIT of Starfleet Battles in college. But never really got into it.
I played a lot of computer games though ( some of them D&D ) and later console games too when they became more elaborate story-wise.
It wasn't until recently that something in my head clicked. ( and also my kids are older ) and I realized that this is the perfect medium for social-interactive-storytelling and immdiately picked up the 4E Quick-Start as a test-run with the family ( and a couple of close friends ) ... this was several months ago.
Granted, my group took to the second game we tried the quick-start for, which was Call of Cthulhu, BUT 4E was our first foray and got us started. Since then we've played Star Wars: saga, CoC and DREAD and we have a great deal of fun....
I guess you could say I did bring in some younger players to the hobby... 12, 15, 17