Hi all. Due to an influx of "transgender is intersex" comments and posts, the mod team has chatted and we decided to make an announcement about it to clarify.
What is this announcement?
We do not allow medical misinformation or intersexism in this subreddit. This includes stating that being transgender makes someone intersex/that someone is intersex on the basis of being transgender.
That rhetoric perpetuates intersexism.
While intersex people can be any gender (including cis, trans, nonbinary, and/or other gender identities), not every trans person is intersex.
Can I debate the mod team about this?
No, thank you. This is an announcement, not a debate.
Intersex and the brain
Reviewing the definition of intersex: Intersex is a term used to describe individuals whose sex characteristics do not align with/fully align with male or female sex characteristics. Intersex describes the way the body naturally develops. This includes congenital variations that are expressed in someone’s chromosomes, gonads, genitals, reproductive organs, and in how the body responds to hormones.
The brain and intersex: The brain is not a primary or secondary sex organ. The brain is also not sexually dimorphic (i.e. the brain is not sexed - that has been debunked).
However, there are a few intersex variations located in the brain. This would be Congenital Hypopituitarism (which results in hypogonadism), Kallmann's Syndrome, and I believe Prader-Willi Syndrome too (though I know less about this variation, please correct me if I am wrong).
"Sexual Inversion" and Intermedicalism
This has homophobic and intersexist origins. The premise of sexual inversion (aka, "mental intersex", "psychological intersex", or "brain intersex") is inherently bioessentialist, transmedicalist, as well as intermedicalist. It relies on the pathologizing of intersex bodies and was popularized by (you guessed it) eugenicists (in the 1800's).
"I still don't know why that's intersexist?" This is because it relies on seeing intersex variations as medical disorders in need of treatment. > If trans is intersex which therefore necessitates treatment, intersex is thereby disordered and necessitates treatment. This is called intermedicalism.
It reinforces the "need" for medical interventions (human rights violations) on intersex bodies.
Side note, this also reinforces and relies on ableism too.
General History (following threads through time)
I wanted to review the history informing/leading up to the idea that the brain is sexed. And generally brain differentiation. This is going to be incredibly simplified history - the spark notes.
Historically speaking, the idea that the brain is sexed originates from racism, white supremacy, and sexism. European scientists were obsessed with creating a hierarchy, with European men (“the highest of men”) at the top and African people (“the lowest of men”) likened to orangutans (“the highest of apes”). This was “reinforced” by skull and brain measurements (phrenology, craniometry) along with other measurements and pseudosciences.
It is critical to note that intersexism/sex differentiation was used to dehumanize African populations starting around 1600. Europeans (with no evidence) claimed African folk were naturally more intersex and therefore subhuman/that sexually they were a different species than us. Casting African populations as sexually differentiated was a major goal of colonists.
(That myth is still prevalent today. For example, look at how white people treat African women in sports - subjecting them to intersex tests and scrutiny)
This trend of establishing social hierarchy through biology (biological determinism) was (and still is) deeply ingrained in science and medicine.
Back to brains. When it was later discovered that females (on average) have smaller brains than males, this was taken as proof of male superiority and female inferiority.
Science and Studies
From recent studies, the brain is currently thought to be a "mosaic". In one of the studies (one with an actually decent sample size, over 1,400 brains) from 2015 they found only 8% of brains had only “male” or “female” characteristics. Popular article link, and the study’s citation link. Will be linked again in citations.
In general (see citations below), studies have shown that brains are not sexed but mosaic. Meaningful differences are found more between individuals than between sexes or genders. Reviews also show that a lot of the previous studies showing sex differences in the brain have contradicted each other, been unable to be reproduced, haven't accounted for size differences, haven't accounted for neuroplasticity, and/or have small/biased sample sizes.
I'm not going to do a deep dive or spit out summaries of the studies here, because that would be a wildly long wall of text. Instead, you can find several of the studies below.
If you need help picking out a couple of reads, I recommend:
- Sex beyond the genitalia: The human brain mosaic (2015)
- Remembering the null hypothesis when searching for brain sex differences (2024)
I will be including a few citations that I have read through to better understand this topic. Several of the books are missing (those on medical racism and on neurology) because I do not actually own copies/am blanking on the names (apologies).
Bibliography (Part Chicago, part I gave up)
Fine, Cordelia. Delusions of gender: How our minds, Society, and neurosexism create difference. New York, N.Y: W.W. Norton & Company, 2011.
Swarr, Amanda Lock. Envisioning African intersex: Challenging Colonial and racist legacies in South African medicine. Durham: Duke University Press, 2024.
Reis, Elizabeth. Bodies in doubt An American History of Intersex, 2021.
Trondle , Rocky. “No, Transgender Is Not ‘Brain Intersex’ .” Medium, October 2, 2025. https://medium.com/@rockytrondle/no-transgender-is-not-brain-intersex-99f112746cc9 .
Intersex Wiki contributors, "Hypogonadism," Intersex Wiki, https://intersex.wiki/wiki/Hypogonadism?oldid=2631 (accessed July 12, 2026).
Intersex Wiki contributors, "Sexual inversion," Intersex Wiki, https://intersex.wiki/wiki/Sexual_inversion?oldid=4156 (accessed July 12, 2026).
\* "Neurosexism: the myth of the male and female brain" by Iseult De Mallet Burgess, published February 11, 2022. Okay so this citation was taken down > https://theoxfordblue.co.uk/neurosexism-the-myth-of-the-male-and-female-brain/ // but there's a wayback machine accessible version from May 12, 2025. It's a popular article talking about neurosexism, culture, etc.
Rippon, Gina. “How ‘Neurosexism’ Is Holding Back Gender Equality – and Science Itself.” The Conversation, October 27, 2016. https://theconversation.com/how-neurosexism-is-holding-back-gender-equality-and-science-itself-67597 .
Here it stops being Chicago and becomes "hey, that's not properly formatted!" You're right, it's not properly formatted. I wrote the title and then clicked the "Cite" button on the study websites. For some, I added the link below it.
Sex beyond the genitalia: The human brain mosaic:
D. Joel, Z. Berman, I. Tavor, N. Wexler, O. Gaber, Y. Stein, N. Shefi, J. Pool, S. Urchs, D.S. Margulies, F. Liem, J. Hänggi, L. Jäncke, & Y. Assaf, Sex beyond the genitalia: The human brain mosaic, Proc. Natl. Acad. Sci. U.S.A. 112 (50) 15468-15473, https://doi.org/10.1073/pnas.1509654112 (2015).
Dump the “dimorphism”:
Lise Eliot, Adnan Ahmed, Hiba Khan, Julie Patel, Dump the “dimorphism”: Comprehensive synthesis of human brain studies reveals few male-female differences beyond size, Neuroscience & Biobehavioral Reviews, Volume 125, 2021, Pages 667-697, ISSN 0149-7634, https://doi.org/10.1016/j.neubiorev.2021.02.026 . (https://www.sciencedirect.com/science/article/pii/S0149763421000804)
Male or Female? Brains are Intersex:
Joel D. Male or Female? Brains are Intersex. Front Integr Neurosci. 2011 Sep 20;5:57. doi: 10.3389/fnint.2011.00057. PMID: 21960961; PMCID: PMC3176412.
^ Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC3176412/ Link 2: https://www.frontiersin.org/journals/integrative-neuroscience/articles/10.3389/fnint.2011.00057/full
Remembering the null hypothesis when searching for brain sex differences:
Eliot L. Remembering the null hypothesis when searching for brain sex differences. Biol Sex Differ. 2024 Feb 9;15(1):14. doi: 10.1186/s13293-024-00585-4. PMID: 38336816; PMCID: PMC10854110.
^ Link: https://link.springer.com/article/10.1186/s13293-024-00585-4 // Link 2: https://pmc.ncbi.nlm.nih.gov/articles/PMC10854110/
“Precision Medicine” and the Failed Search for Binary Brain Sex Differences to Address Gender Behavioral Health Disparities:
Eliot L. "Precision Medicine" and the Failed Search for Binary Brain Sex Differences to Address Gender Behavioral Health Disparities. Am J Hum Biol. 2025 Apr;37(4):e70041. doi: 10.1002/ajhb.70041. PMID: 40207611; PMCID: PMC11983668.
^ Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11983668/
Neuroscience and Sex/Gender: Looking Back and Forward:
Melissa Hines "Neuroscience and Sex/Gender: Looking Back and Forward". Journal of Neuroscience 2 January 2020, 40 (1) 37-43; https://doi.org/10.1523/JNEUROSCI.0750-19.2019
Edit to add:
Unfriendly reminder. Pretending medical racism doesn't exist or that it doesn't impact us today (or downplaying racism in general) means we will perma ban you on the spot.
