It is not who they are. They only perceive it that way. But your sexual reproductive system, Hormones, Dysphoria(Or other disorders), Ethnicity, and background do not make you. The kind of human you are makes you. Your culture, Belief, Religion, Behaviour, and Goals make you. A simple pronoun could never define a person. It is simply not important or "Good" enough to define a person. it does not give the person a personality or change the way they should be treated. It is a mere word in my eyes. But of course, if a person wishes to be defined in a way they have a right to such. It is possible I simply do not understand.