I think when people say stuff like “you’re too young to know you’re gay”, what they really mean is “you’re still young enough to where I can traumatize you by drilling into your head how terrible being gay is and hopefully you respond to it by repressing your sexuality and pretending to be straight.”
My favorite (not) one I got was from my grandmother when I was 15. The conversation went like this:
“So… I’m gay.”
“No you’re not.”
Other people don’t know you better than you know yourself.