Very similar to digest's defining moments, but I also remember very clearly at age about 9 or 10... I was living with my mom and two of my sisters and our new step-dad, and I was always the oddball, but my Dad and brother used to sorta stick up for me a bit before the divorce, but now there was no stopping the onslaught of teasing and bullying from my sisters, and step-dad actually encouraged it while mom refused to acknowledge it happened.
I used to get really upset, but I remember one time when I ran up to my room and flopped onto the floor (as I didn't have a bed... and didn't question at the time howcome I didn't and everyone else did), and I began to cry but within seconds for some reason I just stopped myself and said to myself, "No, I'm not going to cry any more. It doesn't do any good. Emotions are pointless, they don't help anything."
And from that moment on, I never cried again, to the point where many years later I wanted to but found I couldn't.
But yeah, I was always reading and asking questions of the people I felt comfortable with. I was always THINKING questions, though often too shy to ask them, of everyone and everything else as well. I remember thinking that the stuff my parents' religion was teaching me was bullshit when I was about 9, and consciously deprogramming myself from that sorta automatic belief that you do when you're a kid, of asserting my intellect over those little niggles that used to happen when I went against that religion.
I was always learning languages though too. I've never heard of anyone else who read Old French and Anglo-Saxon before their age reached double figures. My interests were very broad and also quite obscure, and never anything like the usual interests for people my age or class.