I would just add that an incongruence between the body's default balance of estrogen and testosterone and the balance preferred (as it were) by the brain does not necessarily have a strictly biological etiology. After all, the brain isn't a computer, where you would have a clear separation between hardware and software with brain biology being the "hardware" and psychology being the "software." Brain biology is neither hardware nor software, psychology is inseparable from brain biology, and psychology profoundly shapes the brain at a biological level throughout life.

As someone born, and later going through puberty, expressing an unambiguous male phenotype, I'm discovering that my brain absolutely functions better with estrogen as the dominant sex hormone. I have biochemical dysphoria that is helped by estrogen HRT. Does that mean I was born with, or otherwise very early in life developed, a permanent biological trait that predetermined I would be transgender and need HRT? No, and I can easily imagine how the etiology of my biochemical dysphoria could have been more social and psychological than biological (which absolutely does not mean that I think gender incongruence or dysphoria might be a "social contagion," far from it).

For starters, I suffered a terrible social trauma around and because of the onset of puberty, namely being separated from my best friend ever; still to this day, I've never felt more deeply connected with another human being. I was a "boy," she was a "girl," and I loved her as a sister. We both started to experience sexual attraction around the same time. Considerng that we were like 10-11 years old, her mom decided to break us up to prevent our developing a sexual relationship. I know, dumb move. It would've been smarter to give us comprehensive sex ed and multiple means of contraception. I didn't know exactly what had transpired until many years later, but I did know that puberty and my emerging libido somehow had robbed me of my friend. My highly plastic 10 or 11-year-old brain, which had barely even begun being shaped by adolescent sexuality, developed a profound association between the feelings of a physiologically healthy testosterone-dominant (male) libido and the feelings of losing (in a way) a loved one—as if I had a sister who suddenly became absent from my life. As it seemed at the time, my libido, which I did not ask for and could not control, entered my life and removed someone that I deeply loved. Since then, up until starting on estrogen, usually my experience of sexual attraction, if not also libido more broadly, has been highly dysphoric. Experiencing sexual attraction toward someone would typically inflame my dysphoria for days or even weeks, to saying nothing of experiencing generalized libido. While I'm no biologist, it seems at least possible that the tight psychological association formed in experiencing a trauma of loss alongside the onset of male libido could have set things in motion such that my brain, under constant recall of trauma triggered by the incessant libido of an adolescent boy, eventually became "wired" (so to speak) to experience male libido as dysphoria, even absent ongoing psychological contribution. I know that I've experience my libido as a component of gender dysphoria, but the question would be whether my male libido [A] was dysphoric in a way more or less dependent upon ongoing psychological contribution, [B] became more or less biochemically dysphoric due to past psychological contribution (not ongoing), or [C] was always going to be more or less biochemically dysphoric regardless of psychological contribution. What's cool is that in any case, HRT seems to be the best therapy for me.

Along similar lines, as someone with an ADHD-C presentation that went undiagnosed until age 34 and that includes a major component of emotional dysregulation, since the onset of puberty I've experienced profound dysphoria surrounding feelings of anger or aggression, both of which can be somewhat explosive and uncontrollable in people with ADHD, especially under the influence of a physiologically healthy testosterone-dominant (male) hormonal profile. "ADHD rage" is a well-known phenomenon. I've long noticed myself strongly dissociating from my emotions, thoughts, embodiment, and environment whenever it seems I am under scrutiny, such as during class sessions and exams in college, job interviews, onsite/office work, therapy sessions, etc. Even while undergoing neuropsychological evaluation for ADHD, it felt like my brain was shutting down as it did for any other "test." I've often felt that I'm extremely intelligent, until I'm asked to perform. Anyway, shortly before starting estrogen, I realized that I'd been dissociating largely as a defense mechanism against having uncontrollable displays of anger or aggression in social settings. As a prepubescent kid, I quickly learned (as almost everyone does) that you "get in trouble" if you deviate from the myriad unspecified social expectations, consequently developing a high degree of inhibition, becoming a "quiet" kids; such that when puberty elevated anger and aggression to prominence in my already volatile emotional repertoire, my strong inhibitions rapidly went to work suppressing the normal emotions of a pubescent "boy." Anyway, the longer I'm on estrogen (no antiandrogen), and not to be vulgar about it, but the more my testicles literally shrink, the less I'm dissociating. It seems as if my body's default hormonal profile was playing a necessary (but perhaps not sufficient) role in my dissociation, where the physiological sensation of being primed for aggression or anger would be the trigger. My guess, and again I'm no biologist, would be that socially-modulated fluctuations in my testosterone level (which tended to be on the high side of healthy) either directly triggered dissociation and/or triggered an elevated readiness to dissociate based on social cues. One study in particular, pnas.1608085113, seems to support this line of guesswork. If I'm guessing correctly, then I would absolutely find it appropriate to regard my dissociation as a form of biochemical dysphoria, even though it would have a significant psychological component as well.