I was going to say 14.
But don't worry dude, I know how you feel. I'm 17 (almost 18
) and look like a frickin 12 year old myself. Haha not to long ago I was at the movies with my friend who is 25 and while waiting in line to get tickets for Resident Evil: Extinction the ticket lady looked at me and asked my friend "Sir...are you alright with your son seeing this R rated movie?"
We both looked at each other and he played up the part of being my dad and said "damnit son, you didn't say this was a R rated movie! that's it...your going to see Alvin and the Chipmunks while daddy sees Resident Evil...and if you give me any lip about it then your sleeping in the oven again tonight!"
The lady had a WTF look and I proceeded to Lol and show her my ID