As far as I can tell, nearly all kids are fairly certain about their gender identity by the time they start school. What makes you so certain that those of them who are transgender will have no idea?
It’s insane to think that kids can be cis gendered because a huge part of what makes us men or women happens during puberty.
So given both of those positions, exactly what point are you trying to make in relation to this thread besides trying to imply that prepubescent transgendered kids don't exist, when they clearly do by their own accounts as adults?
My best friend growing up was gay and some people recognized it before puberty, but he either couldn't or wasn't willing to recognize it until after high school. He had a breakdown while drunk on our band trip and said he was asexual. Do you think a little kid that realizes he's different from everyone else might just think he's trans instead of realizing he's just gay? That's kind of hard to sus out until you actually have sexual attraction to people.