I won't be talking about Tom Serano's biology because it has been shown again and again, for example in the links in this post by @heathercho, that he knows fuckwit. My issue is with his metaphysical claims. Serano asserts that the "gender-sex distinction is rooted in Mind-Body Dualism", but this cannot be right because genders are social roles, and social roles (the expectation to do something in society) presupposes the existence of a body -- indeed, the existence of more than one bodies, for there can't be a society with a population of one.

Serano is right in that Mind-Body Dualism is unpopular in both Philosophy and Feminism (Science never had patience for it at all), but guess what, troons are the strongest believers of Mind-Body Dualism! Just ask a troon where is his "femaleness" located. It can't be in the body, because Biology is transphobic (not to mention that, by popular assent among troons, a troon is not any less trans because he doesn't take estrogen and has no plans to get a dickchop). It can't be in society, because society expect them to take up male roles. His only recourse is to admit that it is all in his mind (or in mental constructs such as language), and that his mind is independent from his body, each has its own identity.

Prove to me that Mind-Body Dualism is true and I might re-evaluate the assertion "trans women are women".