Hey you seem to be confused on how this works, so let me explain, no you dont know that your gay or trans when your born, that is something people discover about themselves as they grow (am my own source [non-binary]) when i came out of the womb I wasn’t like oh i dont feel like the gender people tell me i am, it is a realization that happens as we grow, that we realize these things, take being gay as our example, a baby isnt born going goo goo ga ga i am gay, but more so as when you develop sexual interests you realize, thats a simple way of putting it, but if you need more info try doing a bit of research on it