This has been a surprisingly contentious subject, probably for all of human history. First, I need to define a couple of terms as they are used in the relevant scientific and professional literature. Since the influential 1955 work of Dr. John Money, scientific usage has tended to crystallize a linguistic divide. This Wikipedia article explains it fairly well. Biological sex refers strictly to reproduction-related biological differences, and purely biological expressions of those differences. Gender perhaps began as a euphemism for sex, but now refers to self-perception and to roles.
The biology of sex has never been simple. It is much less simple now, following significant research in the area. It has never been binary. We just understand the details much better now. Here are some broad-brush overviews reflecting current science.
The first video is from the perspective of the medical establishment. The big secret is how many people are so ambiguous biologically that doctors so often have no basis for declaring a binary assignment, and evel less basis for deciding what, if anything, to do about it. No one talked about it. Well, now we are just beginning to talk about it and therefore learn about it.
The second video is more from the perspective of the person, less from the medical profession. The disdain for medical 'fixes' is palpable. The absence of people praising the heritage of Dr. John Money is stunning. He chose fame over science and honesty.
Please let me know if you can't view the testimonial because of Facebook permissions. Nathan gave me permission to republish it. He provided the other two references.
I'm encouraged by the limited trend away from referring to these genetic, epigenetic, and developmental differences as disorders. I hope that improving scientific understanding reinforces this trend, and leads society away from its perceived need to unnecessarily 'fix' these variations. I especially hope society abandons its ancient penchant for demonizing these and other variations. We have already begun to improve our response to things like autism, though we still call it a spectrum disorder. I hope this can become just one more way that we cause (or allow) the morality of our society to improve.
The final straw was watching The Imitation Game, a movie of the story of Alan Turing. Despite his genius, his computer science contributions, and his single-handed cracking of Enigma (saving 14 million lives by shortening WW II by 2 years), his reward was to be forced into hormonal 'treatment' for a year, leading to his (likely) suicide a year later.
Another good article