@ErrorCode
It's so nice seeing parents put their pride before their kids' respect, trust and mental wellness. You don't throw an infantile tantrum of a power trip and "come down" on it, you talk it out like an actual adult; end of story. I don't care what the age.
I agree regarding Tiktok, though - a fine source if you're looking for opinions, but certainly NOT a good reference for facts. That said, she is actually correct on this one.
While I've been aware of this for a while, I decided to check Google just now to make sure I could point people toward it.
Sniffing around on Google very lightly just now led me to "the spectrum model of sex, gender and sexuality", and academic sources as well as various other article sources are pretty uniformly stating exactly what she said: sex is a spectrum. There's even talk about XY women getting pregnant - and I'm not talking about AMAB (assigned-male-at-birth) women, either... pretty sure that one hasn't been done yet, but don't quote me on that.
I'm not really sure I could dig it back up, but my introduction into the Spectrum Model was courtesy of a biologist who posted a rather expansive thread on the matter over on Twitter, and something that caught my eye was a graph they included showing that the spectrum looks more like a camel's back: what are recognized as "male" and "female" - even themselves including a broad spectrum of distinct patterns in sex-related biochemistry and neurochemistry - are ultimately just peaks in the spectrum, which valleys out in the middle and on the sides (don't ask me about the sides, I may have heard of super-polarized sexes or something, but if so that was a long time ago, probably on an episode of House, M.D. thus to be taken with a grain of salt, and ultimately I'm not well-versed enough to discuss whatever it is that lies on the periphery of that spectrum.).
Oh
ErrorCode, you really need to do more than "sniffing lightly around Google" if you want to disprove that sex in humans is binary and immutable.
If you understood sex differentiation then you would know that "an XY woman giving birth" does not disprove the sex binary.
Sex chromosomes are the starting point of sex differentiation.
Male-bodied and female-bodied people are the end point of sex differentiation.
Which is why an XY-woman giving birth is neither impossible nor proof that sex is a spectrum. An individual born with complete gonadal dysgenisis (the XY-woman in question) has a female body and so falls firmly on the female side of the human sex binary. FYI, there is a total of one (1!) reported case of an XY-woman becoming pregnant unassisted in the medical literature to date. This is extremely rare precisely because sex differentiation in a XY-woman which has not followed the usual pathway that more than 99% of XY- individuals follow, does not normally result in a fertile woman able to get pregnant unassisted.
And yes, there have been various people claiming that sex is a spectrum. Invariably they fail to demonstrate the veracity of their claims and are easily disproven. I guess you didn't see that.
My favourite claim came from Alex the pediatrician who was adamant that sex was a spectrum. He later apologised and admitted it wasn't a spectrum after his university professor expressed her sadness that she didn't teach him well enough.
We discussed that fella here www.mumsnet.com/Talk/womens_rights/3975181-Paediatrician-claiming-sex-is-a-spectrum
We pretty much discussed and/or rebutted every one of the popular threads or articles claiming that sex is a spectrum here on FWR. I'm sure we can link you to the Mumsnet thread if you tell us which Twitter thread impressed you so much.