Well I say knows... He now knows as much as I do.
Basically he made the accusation in a private conversation that he thinks I'm a transsexual subtexting it at first then making it obvious what he meant. Tired of dodging the issue by outright lying, Or glossing over the issue with humour I just didn't deny it I wasn't in the mood. He's probably the closest thing to a "bestfriend" he's certainly the oldest friend I have, having known him since I was 4. I was kinda surprised he jumped the issue I convinced myself If I told him he'd just dismiss the idea as silly or confused. Although this same friend was one of the only people to find out about my self harming years after I started.
"Stop acting so erratic and irrational about this, Suppose it's a good thing your not a woman otherwise it would be a million times worse."
"It must be a gender balance issue, Because if statistics are to be believed they walk better on stilts, and drive much more rationally. I guess I'm just a shabby specimen of manhood."
"You actually begin a woman all along... a strange thought, but not completely unbelievable."
To which I said nothing to intentionally incriminate myself. I could have joked it off but didn't.
The conversation obviously got deeper and I told him that it's a confusing issue for me and despite suspecting begin a transsexual it's only my "best guess" and I'm unwilling to say anything to anyone until I can confirm it myself due to the potentially hostile environment also asking him not to say anything to anyone else. I did also ask where he got his initial suspicions. He referred to an event that happened years ago and I'd actually totally forgotten.

we were both 15 and in secondary school we were in a drama performance for Drama GCSE. While casting for the class performance (I believe it was "Lizzie Borden") The cast list specifically called for 12 girls and there were only 10 girls and 2 boys. (Me and him) I said quite openly "I don't mind having to play a girl I've already been practising" my friend also joked "I will only play a girl on the weekends." everyone laughed the teacher then said. "Now now it's quite ok I will just rescript those two parts for male roles."
While everyone was still laughing apparently he noticed the screwed up backwards way my self confidence works. Where laughing mocking my masculinity seems to make me more open and confident, While conversely complimenting me on how "Masculine" my actions have been even in a positive sense makes me even more shy and withdrawn as it hurts my confidence... This effect usually mistaken or masked as humility instead. But this seen for what actually happened.
Me = Suggested to be "Feminine & Passive" =

Me = Suggested to be "Dominant & Masculine" =