JKR’s Claims Part 4: Biology

Katy Montgomerie
4 min readJun 23, 2020


Biology is complicated

Recently JK Rowling, author of Harry Potter, tweeted some transphobic statements and dogwhistles on Twitter that I have addressed here. After a few days silence she wrote a lengthy post trying to justify her position on her website. This is part 4 of my series addressing the claims in her piece. You can see the full thing here.

Speaking as a biological woman, a lot of people in positions of power really need to grow a pair (which is doubtless literally possible, according to the kind of people who argue that clownfish prove humans aren’t a dimorphic species).

As someone who is an avid lover of biology, I find the GC ignorance of biology, and their blind faith that it agrees with everything they already think, very frustrating. Almost daily I encounter people making claims about biology with 100% conviction that can be shown to be wrong with a 30 second Google search. I am aware this quote is an attempt at a joke, but also I feel this is illustrative of the general GC level of understanding of biology (and of trans rights).

Clownfish are one of the many animals that changes sex in the wild, often due to population changes. They are a clear counterexample of the claims “no animals change sex” or “sex is an immutable binary”, but this is nothing to do with sexual dimorphism, which is a measure of differences in appearance between males and females of a species. Of course humans are sexually dimorphic! Men and women look different. Men are generally bigger and hairier amongst other things. Humans are less sexually dimorphic than say anglerfish, where the females are over ten times as long, and more sexually dimorphic than ladybirds where the males and females are almost identical.

The male angler fish is tiny. Even experts struggle to sex ladybirds

There are some animals that change sex that are more sexually dimorphic than humans, like Anthias (show below). They clearly have visible differences between males and females, but also clearly there is not a strict unchangeable binary between the two as there will be a transition process when the female turns into a male. The fact that human sexual dimorphism exists and is so comparatively low is how transition can work at all.

All male anthias were born female

I also fund medical research into MS, a disease that behaves very differently in men and women

But like all of the misinformation in JKR’s post, these claims aren’t just frustrating, they are also dangerous. Some medical conditions vary greatly between men and women and this is a perfect example of where treating sex as a strict binary greatly harms trans and intersex people. Sometimes the difference between how men and women react to diseases can be down to chromosomes, sometimes it’s down to hormones, sometimes it’s down to particular organs, sometimes a combination of those things, sometimes it’s something else. Also it is often social too, and factors such as occupation, habits and diet play a role.

When the coronavirus news hit that men are more likely to die from Covid-19 than women, the almost unanimous immediate Gender Critical reaction was to claim that trans women would die at the same rate as cis men “because biology”. Then days later, scientists, including those at the NHS, announced they were trialing giving cis men estrogen therapy as a treatment, something which the majority of trans women are already on! Other researchers also showed that smoking, something that men are more likely to do, was a factor. The reality is, as I have said several times already, biology is very complicated. It is likely we won’t know all of the mechanisms involved that cause the difference in mortality rates between men and women for years, but to just blindly assert that trans women are the same as cis men reduces their chance of getting good treatment, and even harms study potential.

Full post | Part 1 | Part 2 | Part 3 | Part 4 | Part 5 | Part 6 | Part 7 | Part 8 | Part 9 | Part 10



Katy Montgomerie

Katy is a feminist, LGBT rights advocate, atheist, metalhead, insect enthusiast and trans woman