This is actually a very fundamental question of nature or nurture. You, and the movement of LGBT people, believe that it is nurture, and innate. Perhaps wrong brain in the wrong body, perhaps hormones, perhaps chemicals. However my position is that it's a mixture of the two, which doesn't make anyone's feelings less valid, but just means we should think twice before pumping children full of hormones (or blockers) and make sure it is something that cannot be treated with social/psychological care. If there is an element of social contagion (remember how cool anorexia used to be? Emo adjacent things?) then we have a disaster on our hands, so we should exercise precaution first.