LGBT Civil Rights and Activism

As you pointed out, all fetuses start out with the same anatomy, and some develop in such a way that they are born with anatomy that does not clearly correspond to either side of the gender binary. (The term for this is intersex.) Those who insist on the gender binary and want to put everyone in a little box labeled XX or XY conveniently ignore the existence of intersex people. However, they do exist, and imo, their very existence is evidence that the gender binary is an illusion, and that we need to take a broader view of what gender is and how it may or may not correspond to an individual's genetic makeup.