Have I completely misunderstood GCSE biology...

[proximalhumerous]

...or is the purpose of spotting an anomaly not specifically to disregard it in order that it doesn't lead to an inaccurate conclusion?

If so, why is everyone fixating on DSDs as "proof" that sex is a spectrum, when the anomalous 1.7% (if indeed it is as high as that - from what I've read that figure is only achieved if you include conditions such as PCOS which have a tenuous claim at best to be one of the "intersex" variations) is clearly a set of results that don't fit. Because something has deviated from the norm. It's not like calculating the mean of a range of heights, FFS.

Please can someone more scientific than me explain what is going on here? Or is it simply that certain factions are so hell-bent on arguing that anyone with ladyfeels can be a woman they're happy to completely disregard any sort of science or logic in order to do so?

Totally.

0.02%

It's certainly possible to have extra chromosomes, but that doesn't necessarily extend the argument for 'sex is a spectrum'. After all, we don't usually consider Down's Syndrome to be part of the rainbow spectrum. At least not yet. Mind you, if you can warp PCOS into the rainbow, anything's possible.

PCOS an intersex variation?? wtf???

Yup. As a woman with PCOS I find this so fucking offensive.

I came across a TRA (TIF) on x claiming that endometriosis was an intersex condition

And kittens are definitely small asteroids.

All this isn't coming from anywhere rational, balanced and healthy. It never is.

I’m not sure why GCs don’t put the argument to bed by stating chromosomes are how a persons sex can be determined (should there be any doubt).

More than 99.98% of people have xx or xy chromosomes. Of the 0.018% who don’t, many or most won’t have a trans identity. This group are the group where I think a ‘case by case’ basis might apply and having an ‘assigned sex’ might be appropriate

You can’t put an argument to bed when someone doesn’t care about facts or listening to, when someone isn’t arguing in good faith but instead using emotions to carry their view

That exactly. Look at the flailing at the Cass report.

This is a movement rooted in feelings creating reality and in trying to control and bully everyone else into enablement. It cannot be reasoned with, facts and resistance are 'hate'.

'GCs' have put the argument to bed - there is a fixed, biological definition of sex detemined by known genes (which in almost all cases are carried on specific chromosomes) that direct embryonic development along the Wolffian or Müllarian pathway. The courts agree, and have provision for evidential determination of sex if required for people.with the more difficult DSD conditions.

Unfortunately the TRAs have a shape-shifting, caffeine-fuelled toddler instead of a logical agrument, and putting that to bed is a different matter.

And women are disadvantaged when trying to argue the emotional case because we are seen as emotional and irrational and therefore our feelings and emotions can be dismissed

😂 this is so beautifully and accurately put!

Possibly that poster ( @CosyLemur) is 46XX/46XY rather than 48XXXY though?
https://en.m.wikipedia.org/wiki/46,XX/46,XY

I think when people on here are talking about sex development and DSDs they often forget about chimeric and mosaic conditions which can affect the sex development of a very small number of people.

One of the ways these sort of conditions can occur is in the case of non-identical twins, one male and one female, fusing at an extremely early stage of development. Anyway, for this and other reasons, some people can have be XX in some cells, tissues or organs and XY in others.
Depending on the cell lines involved the sex organs may or may not be affected. Even when they’re not, it can cause confusion and complications (look up the case of Lydia Fairchild).

In some cases (extremely rarely) these conditions mean individuals can have an ovary and a testis, or an ovotestis. This is called true hermaphroditism.
“True hermaphroditism is a disorder of gonadal differentiation characterized by the presence in the same individual of both testicular and ovarian tissue.”
[Urologic Surgical Pathology]

In true hermaphrodites, fertility is usually compromised but there have been some pregnancies reported and even fewer instances of fatherhood. In exceptionally rare cases the literature has mentioned that both sperm and eggs seem to have been (possibly) produced in a single individual. I don’t know how that works in terms of hormones but some evidence of it has been reported, so…?

All this has nothing to do with trans people and sex is still a binary but it is complicated. I am GC but also a biologist and oversimplification (and accusing people of lying) doesn’t really help anyone.

Just to add…you can get chimeras when both twins* are the same sex too of course, but they don’t have the potential to cause the same sort of problems in sex development. Identification using DNA tests can cause problems though. The Lydia Fairchild case, mentioned above, is an example of this.
(* there are other mechanisms by which chimeras occur also)

What's more common, chimerism and mosaicism, or trans activists lying and appropriating other people's medical conditions

I am sure some transactivists lie, as do all people, and for other TRAs their world belief just doesn’t align with reality.

There has been quite some misinformation posted on this thread too though. People seem to be unaware of rarer conditions, which isn’t too surprising. But if you’re not an expert in something then you shouldn’t use that subject to try to score points. That works both ways.

It’s not fair of posters to accuse a pp of lying when they describe their own perfectly plausible, albeit rare, medical condition. Is pp telling the truth? I don’t know, but they certainly could be.

@Cappuccinosisters

"Anyway, for this and other reasons, some people can have be XX in some cells, tissues or organs and XY in others."

But they never have neither, or both at the same time, or other. It's always either XX or XY: the inevitable sexual binary.

"In exceptionally rare cases the literature has mentioned that both sperm and eggs seem to have been (possibly) produced in a single individual. I don’t know how that works in terms of hormones but some evidence of it has been reported, so…?"

So we shouldn't say that it's impossible for a single person to produce both sperm and eggs. That's true. In extremely rare cases where a single body is in fact a mash of two bodies, both part-bodies may end up producing their own organs. But each of those mixed bodies sticks entirely to the binary nature of sex. Even in the case of "true hermaphrodites", the ovary will be constituted of XX cells, and the testicle of XY cells. There's no deviation from the path determined by the cells' chromosomes. There can't be, because sex is a binary in nature.

Yes, I agree sex is binary in nature @Seethlaw. I already said that.

Usually an individual cell will be XX or XY, though occasionally they can be X or XXY or XYY or even more rarely XXXY etc.
And usually the (nucleated, somatic) cells in a person’s body will all carry either XX or XY (or occasionally XXY etc).

However at the level of an individual, a person, there can occasionally be a mix of XX and XY cells in the body. I don’t think everyone on this thread was aware of that, it sounded like they weren’t anyway.

But they never have neither, or both at the same time, or other. It's always either XX or XY: the inevitable sexual binary.
Yes, at the level of cells, (at least usually, unless they’re XXY etc as mentioned above).
At the level of a person it can get more complicated sometimes.

I should also add that a chimera doesn’t always arise because of twins fusing at a very early stage. That’s one mechanism but there are others, so the ‘mash of two bodies’ description isn’t always appropriate iyswim.

@Cappuccinosisters

"However at the level of an individual, a person, there can occasionally be a mix of XX and XY cells in the body. I don’t think everyone on this thread was aware of that, it sounded like they weren’t anyway."

It's always better to be properly informed, so I at least thank you for speaking up on this matter!

"I should also add that a chimera doesn’t always arise because of twins fusing at a very early stage. That’s one mechanism but there are others, so the ‘mash of two bodies’ description isn’t always appropriate iyswim."

Yeah, I see what you mean, and I apologise for using a simplistic image.

In exceptionally rare cases the literature has mentioned that both sperm and eggs seem to have been (possibly) produced in a single individual.

My added emphasis. Have you reference for this, because I've never found one with decent evidence in anything that could count as a reputable journal? Nearest I got was 2 people with apparently complete ovaries and testes, but one* *only produced eggs and the other only produced sperm. (And even that I lost the ref for and haven't been able to find again).

But even if it has happened very occasionally, it's a 1 per several billion event. Exactly the sort of disregardable anomaly the OP is talking about.

To be honest the reason I added ‘possibly’ here is I haven’t read the papers themselves, just some of the abstracts, as they’re behind paywalls. So I’m not certain how reliable the evidence is but it is peer reviewed.

eg https://pubmed.ncbi.nlm.nih.gov/28282768/

I agree about rarity obviously.

It is still true that humans are a bipedal species even if some people are born without legs. The difference is nobody denies the existence of those people, and I think that does happen sometimes wrt people with rarer DSDs in the sort of online discussion we’re having here. And it really shouldn’t.

I do remember reading a report previously where sperm was produced and images of the ovary suggested that eggs had previously been released (I think). I’ll see if I can find it later.
This really would be exceptionally rare I would think though, if it does indeed occur.

But my main message is that some people (rarely) have a combination of XY and XX cell types, and this is not in dispute.

In the end though, outliers are just that. They have nothing to say about the binary nature of sex, nor about the gender identities personalities of people.