I'm 31 and I recently was told I needed a parent's signature to renew my library card - until I produced my driver's license. Oooooh the shock! Although I didn't like looking 12 when I was 20, looking 16 when you're 30 isn't all bad!
That's great. It's funny how that works isn't it? When you're young and you're told that you look younger than you are, it's an insult. When you get a little older, it becomes a compliment.