(This is one of Seven Answers).
As a teenager, I would not/could not admit that I was gay. I transferred the urges which I felt for certain teachers and classmates into 'wishing I could be them,' wishing I could magically inhabit a bigger/stronger/handsomer/more mature man's body, escaping my own which I felt to be small/weak, unattractive/immature. None of this was true, of course, but one makes 'deals' with one's inner voices when one is learning how to be an adult human being... Then at the age of eighteen, during my first month of my first year at university, I met a man - no, this isn't that sort of story. He was a floor captain of my dormitory, and all he did was help me get back into my room one morning when I was accidentally locked out. But he was tall, handsome, bearded, funny, smart... only two years older than I was, but I automatically filed him in the 'adult' category (as opposed to me in the 'boy' pigeonhole). And yes, I would have liked to have (somehow, magically) inhabited that big golden body... but that evening, while working myself up to my usual pleasurable nighttime experience (ahem!), I found myself not wanting to be him but to be in bed with him... making love with him. It was the first moment when I realised that I was gay, and that such things were open to me.