Emma Hilton Profile picture
Sep 20, 2020 13 tweets 2 min read Read on X
Three years ago, the Conservative government launched a consultation on a somewhat esoteric piece of legislation concerning the rights of trans people to alter their birth certificate and legal sex.
The proposed changes included ‘self ID’, a radical departure from the current system of careful assessment and mindful transition for those suffering dysphoria.
Self ID would have allowed acquisition of legal sex based on no more than a sworn declaration. But, in reality, the sworn declaration was lip service.
The proposed changes would have, de facto, removed, or at least critically compromised, protections afforded by equality legislation on the basis of sex.
‘I am a woman’ would become sufficient to permit access to legally-protected female spaces.
Three years ago, women realised this might be a problem. Many had seen it coming for a long time, but the potential impact of these legislative changes raised an army.
Women said ‘No.’

Not just famous women expert in the politics and theory of gender, but women who had gone about their lives without even realising that these protections apply to themselves each and every day.
Women took to the streets, handed out thousands of leaflets and wrote thousands of letters, raised awareness, lobbied their government representatives, dissected the legal ramifications.
Today, following weeks of leaks and rumours, it seems that Self ID has been scrapped as a mechanism to acquiring the opposite legal sex.

For me, it has been too bitter a fight to evoke much positive emotion.
The three years of campaigning and lobbying has created a climate among service providers such that ‘I am a woman’ is indeed sufficient to permit access to legally-protected female spaces.
I hope this newly-invigorated movement of women, connected in ways unimaginable a few years ago, can stay the course to ensure equality legislation is not only secured but reinforced.
The prison service has reviewed its position on the transfer of transwomen to the female estate. Sporting federations are beginning to revisit their regulations for the female category.
Sex shouldn’t matter half as much as it does, but there are, in my opinion, a small number of situations where it will always matter, and where female protections are necessary.

Let’s see this through.

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More from @FondOfBeetles

Apr 8
A cell layer that has developed to protect your body from the outside doesn’t work like a cell layer that has developed to protect your body from the inside.

The cells lining my vagina are not the same cells, and they don’t have the same function, as the ones wrapping your penis.

There’s a name for what happens when you subject dry-adapted “outside skin” to wet-adapted “inside conditions”.

Further reading: trench foot.
My vagina - “inside skin” - hothouses a healthy microbiome that promotes health and healing, and imparts immune function onto small humans that happen to come out of it.

Yours? Less so.
My vagina is a muscular organ, adapted to my healthy female function of receipt of peen, expelling menstrual products and pushing out small humans.

An inside out penis? Less so.
Read 8 tweets
Apr 3
Let’s move the discussion from available techniques for sex screening and to matters of process.

Ross @Scienceofsport has described the need for detailed technical documents that inform sports federations in robust implementation of a sex screening policy. I’ll link to his video next.

But here, I’m going to take a wander through running an assay, highlighting standards and procedures.
First, this is Ross’ video of the overall process, highlighting the need for coherent implementation practices. He - correctly - evokes the reams of technical documents used by WADA in their anti-doping programmes.

Even the simplest of lab assays can have pages of instructions associated with it.
So, the assay for sex screening will be detection of the SRY gene. This is the ‘make male’ gene that is the master switch for testes-not-ovaries.

The assays out there are very sensitive and specific. That means they can detect SRY when it’s present, and they don’t give a signal when it’s absent. They aren’t 100% on either metric, but near as dammit.

This itself may be a problem…
Read 18 tweets
Mar 26
In 2025, Jon Pike and I argued that exclusion of athletes with androgenising XY DSDs from female athletics is justified, because these athletes are male, not female.

@runthinkwrite

tandfonline.com/doi/full/10.10…Image
@runthinkwrite This followed a 2024 paper where we, along with Ross Tucker, Tommy Lundberg, Cathy Devine and many others, argued for a return to sex screening to secure eligibility for female sport.

@Scienceofsport @TLexercise @cathydevine56

onlinelibrary.wiley.com/doi/epdf/10.11…Image
@runthinkwrite @Scienceofsport @TLexercise @cathydevine56 This followed another 2024 paper where we critiqued the (now former) IOC policy on inclusion of trans-identifying males in female sports.

onlinelibrary.wiley.com/doi/epdf/10.11…Image
Read 5 tweets
Feb 6
I am starting to pull out details of this "meta" review that says trans-identifying males don't have advantage over women in sports.

I need a sanity check, because I'm only at Figure 1 and already there's an issue.

bjsm.bmj.com/content/early/…
So this is Figure 1A: fat mass (kg).

Alvares 2025, n=7, fat mass is higher in females as both absolute and relative values. This is logged as "favours cisgender", which is kinda odd because high fat mass isn't usually considered favourable for sports, but whatever.

TIMS: 16.2 kg (24%). F: 19.5 kg (26%).Image
But Ceolin 2024 is also logged as "favours cisgender" when their values are:

TIM: 18.2 kg (24%). F: 15 kg (25%). Their n = 47.
Read 7 tweets
Feb 4
What an insane bunch of cherry-picked metrics, cobbled together to try and argue that trans-identifying males should be in female sport.

bjsm.bmj.com/content/early/…
There are little-to-no controls for physical fitness in the individual studies.

Yet they conclude: “transgender women do not exhibit significant differences in upper-body strength, lower-body strength or maximal oxygen consumption relative to cisgender women after 1–3 years of GAHT.”

You haven’t controlled for fitness!!!
Their "performance" data. Can you see one study that really sticks out as an outlier? Image
Read 10 tweets
Nov 4, 2025
The claim that won't die: trans-identifying males are "underpowered" and therefore "disadvantaged" in sport.

"One can imagine a large car with a small engine competing against a small car with a small engine, and that summarizes the playing field." Joanna Harper, Huff Post, 2016.

"You have a bigger body, and you have a smaller engine to move that vehicle around." Yannis Pitsiladis, BBC, 2019.

"giving trans women the disadvantage of having to power larger skeletal frames with reduced strength and aerobic capacity." Jamie Agapoff, 2025.
What happens when a trans-identifying male suppresses testosterone?

They lose a bit of muscle mass.
Their haemoglobin drops to female-typical levels.

The claim that won't die rests on the idea that trans-identifying males retain their skeletal frame and most of their muscle mass, but become unable to move it around a sports fields, rendering them "disadvantaged".
The words "underpowered" and therefore "disadvantaged" are carefully chosen, and typically leave the reader to infer that this means "underpowered" and therefore "disadvantaged" compared to females.

So it's fair to have them in female sport, right?

Wrong.
Read 10 tweets

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