It sounds like the lesson could've been a bit more nuanced. They could've said that some people know right away and others have to self reflect. I'm not trans, but I'm gay and it took a lot of reflecting to figure that out, especially because neither of those things were really talked about when I was growing up. I could just tell I was different from the norm in some way, but it took a lot of confusion before figuring out exactly how I was different.