I was, in a previous life, a teacher. It was very obvious to me - usually by the time a child was around 10 or 12 whether they were LGBTQ+ - what I can say is that over my decade or so of teaching (2004-2018), the speed at which those children realise and the acceptance of their peers has both improved drastically. That’s all to the good. You cannot tell or even hint to someone what their sexuality might be; particularly children. The one time I did it as an adult, the friend in question was livid, went into denial and went off like a bomb. People are more complicated on the inside than the outside and when faced with the ‘what do you think?’ - the correct answer is often ‘you’ll work it out’ with perhaps a misplaced twinkle behind the eyes.
Welcome to the party - if it helps, I found out you were gay from reading this article, so you beat me to the party. :o)