Oh I have theories about gender, but alas I'm too tired to elaborate much right now. Suffice it to say, I think which gender we identify with (I.e. what people, and only then by extension, sociocultural concepts, our ideal self-image is shaped in dialogue with) is probably innate (and I have a whole etiology for this), but what gendered behaviors and expressions and identities and ways of being we adapt from that identification come from gender as a sociocultural construct, which is largely "arbitrary", multifaceted, and so on. This does not mean you can arbitrarily change or remove people's identification with other people, or their desire or lack thereof to express aspects of that concept, however. I think my account of exactly how that cultural construct functions, is identifiable, and what it is, as well as my account of the etiology of gender identification, are probably less rigidly medicalized than Serano's, however. I'm a poststructuralist through and through, and dislike essentialization, and enjoy using tools such as Wittgenstein's language games and family resemblances.