 The same movement now calls on you to say that your own biological sex is totally fluid over the course of your life, even when there is a definitive sex chromosome. So just from the standpoint of hard biological science, for those who are part of the trust the science crowd, it's interesting how quiet they are on this one. There are two hard chromosomes. There's an X and X chromosome, you're a woman, an X and a Y chromosome, you're a man.