GrinWithoutaKat wrote:I'm no biology expert, but don't we all start out female at the very beginning? It's kind of down to chance what gender you develop into. And there seems to be so much evidence for how things can go wrong here. People who on the outside look like one gender, but on the inside have the bits of another. People that have the bits of both. So this stuff definitely goes wrong in our biology, not just some mental illness, and I'm not sure how reliable this is, but wikipedia says around 1.7% of the population (1 in 60) will have some kind of intersex condition.
The biology of sex/gender is really fascinating, so it's frustrating that it's so often misrepresented as "simple" and/or "common sense" by bigots.
You're absolutely right, an embryo early in development has all the prerequisites to develop in either a male or a female way, regardless of whether the ovum fused with a Y sperm or an X sperm. The Y chromosome typically contains a blueprint for a fundamental "maleness" protein. If the chromosome is present and that protein is made, it will bind to a main piece of molecular machinery (called a nuclear receptor) that makes hormones in the embryo, changing which pieces of DNA it gets its instructions from, and therefore causing it to build growth factor hormones that bias undifferentiated gonad cells towards developing into the precursor of testes. If these pre-testes are built, they start producing masculinising hormones that bias the foetus towards the production of masculinised tissues and features.
So you can be intersex in all sorts of fascinating ways -- some of your cells can have XX and others XY, or all your cells can have XXY (an extra chromosome), or your Y chromosome can be faulty, or the growth factors on chromosome 9 can be faulty, or the receptors in the early cells that read which profile of growth factors you have can be faulty, or the receptors that decide to build tissue based on whether you have masculinising or feminising hormones can be faulty...
Being transgender isn't considered an intersex condition in the way that having XXY chromosomes or an insensitivity to androgens is, because the underlying biological events that cause a person to be transgender (whatever they are) appear to happen in the brain rather than in the reproductive system. But it's no big leap to suggest that, in the same way gonads can develop atypically and result in an intersex condition, the brain could develop atypically and predisposition a person towards, later in life, discovering that their internal visualisation of what they ought to be like does not match the body that developed. And there is indeed some evidence that the brains of (e.g.) trans women statistically have female-profile physical structures (think neuron density in certain regions, etc.) -- this is detectable even before a medical transition.
So there's a really strong medical and biological basis underpinning how we can think about gender dysphoria and kind of understand it that way as a condition. There's also obviously a sociocultural aspect to being transgender, because naturally when your self-visualisation is sexed in a particular way - when you feel you are really a certain sex on the inside - then you will want to be treated socially as the corresponding gender and be considered part of that social category; or indeed if your self-visualisation is neither male nor female then you would want to be treated socially as nonbinary. There's no difference between that and how a cis person self-identifies into a gender category (except, I suppose, that they don't have to worry about it as much).
