I recall a common theme when I was growing up (although it seems to have subsided in more recent times) of people (mainly boys) accusing other boys/men of being gay - even if they weren't. All they had to do was look different or come across as slightly weaker, and that would trigger some visceral reaction in some people.
I was savagely a target of this. Mainly because I was a quite introverted kid, who focused in school. Nothing to do with sexuality. But then when I did realize I was bi everything they said became more than just personal.....
"What did they see and know, that I did not know of myself?"