This question made me think about things. I was molested by two slightly older girls when I was six. They were sisters and were seven and nine at the time. I was a willing participant. It lasted for for several months and involved fingering and oral.

When I was twelve, the older girl had sex with me at her house. It was over pretty quickly. The freaky thing is that her mum was in the next room and I am sure she knew what happened.

Prior to that, I started masturbated around nine or ten and had my first orgasm when I was eleven. I was very preoccupied with sexual thoughts and masturbated often.

In spite of all that, I didn't have sex again until I was twenty.