Hey, don't put down looking older than you are... I'm 21 and last spring break on 2 separate occasions people guessed that I was 15 >.< Not fun looking like jail bait when you're far from it.
I don't have a sister. Just a younger brother, and he's bigger (not taller) than me. *sigh* I'm a foot taller than he is, but he weighs more than I do. XD