My parents were nontechnical, but I was lucky enough to have my own computer and a good internet connection starting around 4th grade (8-9 yrs old). Feeling comfortable "breaking" my computer was another thing. I was deathly afraid of breaking things as a kid (unlike my younger brother), and I think it prevented me from coding and exploring things even earlier. I think becoming a great {coder, thinker, leader, etc.} requires internalizing that at some level, it's okay to break the rules.

I eventually found my way onto IRC around age 12, where everyone posed as a 17-yr-old female from LA. I was thankfully super paranoid and fended off child molesters by pretending I was a 56-yr-old man from Texas. ;)