There‘s a horrific amount of magical thinking and plain ignorance among transactivists and young people in general thanks to deliberate and systematic attempt to use these rare medical conditions to give validity to the idea that a person can change sex just by declaring it.

Truth is, because our genes determine sex, and specifically the Y chromosome and several genes on it, whether something goes wrong, or not, all we end up with is exactly what’s encoded in our genes.

For example, in the cases of very rare persistent Müllerian duct syndrome, which is a male DSD, the Müllerian duct doesn’t regress, thanks to absence of anti-müllerian hormone or its receptor. The patients end up with variety of anatomical abnormalities,

Including some kind of uterus/ovary gonad or remnant which is non-functional and carries various health risks. Key to understanding this is that their anatomy and genetics are still fully male, but thanks to a single gene, Müllerian ducts that would normally regress, don’t.

Transactivists have some warped idea that DSDs produce “variety of sexes” they do not. Biological sex entails capacity for reproduction and for the most part, people with DSDs are infertile. And if they are not, then they are fertile as their biological (genetic) sex.

Such as men with Kleinfelter’s an XXY male DSD which typically results in shortage of testosterone so the male body, depending on the severity of the syndrome, fails to properly masculinise. Patients are typically infertile, but when fertile, they are so as males.

And they can suffer with gynaecomastia - enlargement of male breast tissue. These men don’t have female breasts with female mammary glands. They have male bodies that have developend in the absence of appropriate hormone levels. And for this such men can suffer discrimination.

There are other male DSDs whereby, thanks to gene mutations, the body is partially, or completely, resistant to testosterone. The male body fails to fully masculinise, but it does not develop reproductively into a female instead, because male and female are not interchangeable.

In even rarer cases, certain genes from Y chromosome transpose onto an X, so a 46XX DSDs a female embryo recieves instruction to develop down the male pathway. But because they are female, and lacking the rest of Y, the development doesn’t result in a fully functioning male.

This is what we mean when we say DSDs are sex-specific. When things go wrong, our bodies can recieve erroneous signals, or fail to receive the right ones, but our template is always either male or female, and these anomalies can only modify that template.

DSDs don’t “switch” the primary male or female template, they impair it. And even in the case of rarest DSDs called ovotestes (found mainly in female 46 XX or 46XX/46XY chimeras) despite the presence (often within the same gonad) of both ovarian and testicular tissues,

The reproductive organs are typically ambiguous and malformed and the rare subset of patients who are fertile are so as females, not as both sexes. Here’s to give you an idea of the complexity of such a scenario, in 46 XX patient

The take home message here is, our sex is in our genes, and even when some genes get mixed up, the existing template of male (has Y) or female (has no Y) is what determines the type of anomalies of sex development. DSDs aren’t “other sexes”

Just like Down’s syndrome isn’t a separate species of human. To claim DSDs are “other sexes” betrays ultimate lack of understanding of what sex is (reproductive role) as well as ignorance of embryology, which is admittedly a deeply complex science which is hard to understand

In any case, for the last time I beg of you, both children and adults who have no understanding of embryology or medical abnormalities, stop misusing DSDs as some kind of evidence of “sex spectrum” or “more than two sexes”. If sex was a spectrum between male and female

We would be seeing people right down the middle, who can self-fertilise. There are no such cases recorded in medicine. If there was more than 2 sexes we would be seeing people reproduce as something other than males or females. There are no such cases recorded in medicine.

There are no gametes other than sperm (male)and egg (female), There is no sperg, spegg or even egrm. And if you think these words sound stupid, you should watch yourself from a perspective of anyone who has knowledge of DSDs. So please, just stop, this has gone too far now.

ADD: For a more in-depth understanding of fundamentals of biological sex across species and time: https://twitter.com/lascapigliata8/status/1273376495172493312