Overview

Differences (or disorders) of sex development (DSDs) are congenital conditions in which the development of chromosomal, gonadal or anatomical sex is atypical. They are often grouped under the older umbrella word intersex. In debates about gender identity, intersex conditions are some of the most-cited and least-understood facts in circulation: they are used to argue that sex is a "spectrum", that sex is "assigned" rather than observed, and that a gender identity which contradicts the body is simply another natural variation.

This page covers what DSDs are, how common they are, why they do not create a third sex or a spectrum, what is known about gender dysphoria in people with DSDs, and why the history of surgery on intersex infants matters for debates about medical transition. It also gives space to intersex people themselves, some of whom object to being used as an argument at all.

Sex, gametes and development

How biologists define sex

In biology, sex is defined by reproductive function. Humans, like all anisogamous species, produce two types of gamete: small, mobile sperm and large, immobile ova. A male is an organism whose body is organised around the production of sperm; a female is one organised around the production of ova. There is no third gamete, and no intermediate one (Goymann et al. 2023; Wright 2025).

This definition does not depend on any single marker. Chromosomes, hormones, genitals and secondary sex characteristics are the mechanisms and signs of sex, not its definition. That matters for DSDs, because in these conditions one or more of those mechanisms misfires. A person can have XY chromosomes and a female-looking body, or XX chromosomes and virilised genitals — but their reproductive anatomy still developed along one of only two pathways, even when that development is incomplete and the person is infertile.

How sex normally develops

In typical development, the SRY gene on the Y chromosome triggers the early gonad to become a testis, whose hormones build male internal and external anatomy (the external genitals depend on testosterone being converted to dihydrotestosterone, DHT). Without SRY, the gonad becomes an ovary and the female pathway proceeds. DSDs arise when a step in this sequence is altered — by a chromosome difference, a gene variant affecting a hormone or receptor, or a disruption in early embryonic development.

The main conditions

The 2006 Chicago Consensus (an international expert statement on the medical management of intersex conditions) replaced older terms such as "hermaphrodite" and "pseudohermaphrodite" with DSD, defined as congenital conditions "in which development of chromosomal, gonadal, or anatomical sex is atypical", and classified them by karyotype (chromosome pattern) (Hughes et al. 2006). The conditions most often invoked in gender debates are summarised below.

A few points stand out. First, nearly every DSD is sex-specific: CAH virilises females; androgen insensitivity and 5-ARD under-virilise males; Klinefelter affects males and Turner affects females. The conditions are described in medicine as variations of male or female development, which presupposes the two categories rather than dissolving them. Second, Klinefelter and Turner syndromes — often cited as "XXY people" and "X0 people" who are "neither male nor female" — produce bodies that are unambiguously male and female respectively; many affected people only find out during fertility investigations.

Third, even ovotesticular DSD, the closest humans come to the old idea of a "true hermaphrodite", does not produce a third sex. In this condition the ovarian tissue is the part most likely to function: a 1994 review of 283 published cases found the testicular tissue usually immature, with spermatogenesis reported only twice, while 21 pregnancies were reported in ten individuals and only one person had apparently fathered a child (Krob et al. 1994). Nothing in that literature describes a person fertile both as a mother and as a father. Even if one did, that would be a person with both kinds of gonadal tissue — not a new kind of gamete.

How common are DSDs?

Two estimates, one hundredfold apart

The figure most often repeated online is that 1.7% of people are intersex — "as common as red hair". It comes from a 2000 review by biologist Anne Fausto-Sterling and colleagues, which counted any individual who "deviates from the Platonic ideal of physical dimorphism at the chromosomal, genital, gonadal, or hormonal levels" (Blackless et al. 2000).

In 2002 the physician and psychologist Leonard Sax showed that this figure rests almost entirely on its definition. About 88% of the 1.7% consisted of a single condition, late-onset CAH, in which genitals are normal at birth and many people never have symptoms. Klinefelter syndrome, Turner syndrome and other sex-chromosome variations made up much of the rest. Sax proposed that "intersex" should be restricted to conditions in which "chromosomal sex is inconsistent with phenotypic sex, or in which the phenotype is not classifiable as either male or female." On that definition, the prevalence falls to about 0.018% — roughly 1 in 5,500 births, "almost 100 times lower" than Fausto-Sterling's estimate (Sax 2002).

Why the difference matters

The disagreement is about definitions, not data: both used largely the same incidence figures. Some advocacy groups keep 1.7% deliberately: Intersex Human Rights Australia recommends citing a range of 0.3% up to 1.7%, keeping 1.7% as the upper bound, because it captures everyone at risk of stigma due to innate sex characteristics (IHRA, Intersex population figures). Human Rights Watch and interACT (a US intersex advocacy group) also use the 1.7% figure in their public materials (HRW; interACT).

The problem is what happens when the broad number travels into a different argument. "1.7% of people are neither male nor female" is false on any definition: the people who make up nearly all of that 1.7% are unambiguously male or female, most of them fertile. The figure is often used to suggest that sex is so blurry that anyone's gender identity could just as plausibly be "real" as their body. Several commenters on /r/detrans describe seeing the label stretched further still, to common conditions such as polycystic ovary syndrome:

I met some women with PCOS who claimed that this condition made them intersex🤡 of course. These women called themselves nonbinary and said that for them being nonbinary is biologically justified because they're "intersex." PCOS is NOT intersex. You're just women! —thistle_ev, detrans female

Why DSDs do not make sex a spectrum

The claim that intersex conditions prove sex is a spectrum is the central argument this page has to address. It deserves a careful answer rather than a slogan, because the facts it starts from are real: sex characteristics do vary, and some people's bodies are genuinely hard to classify at birth.

Variation in traits is not variation in category

Almost every trait influenced by sex — height, voice, body hair, hormone levels, genital size — is bimodal: it varies within each sex and overlaps between them. That is a statement about characteristics. Sex itself is the category of reproductive function those characteristics serve, and that category has two members because there are two gametes. A tall woman or a man with breast tissue is not "partly" the other sex. In the same way, a woman with CAH whose genitals were virilised before birth is a woman with a disorder affecting her genital development, not a person located somewhere between female and male. As one desisted commenter put it:

Sex is not a spectrum. If it were, we'd see a spectrum of gametes. But we don't; there are only two. The fact that a small number of people have disorders of sexual development does not disprove this. —Hardwired-666, desisted female

Infertility does not remove sex

A frequent rebuttal is that many people with DSDs cannot produce gametes at all, so a gamete-based definition "excludes" them. But the definition refers to which reproductive pathway the body is organised around, not whether it currently works — just as an infertile man, a woman after menopause or someone who has had their ovaries removed has not changed sex. A person with CAIS has testes, not ovaries; a person with Turner syndrome has (failing) ovaries, not testes. The pathway is identifiable even when it is incomplete (Wright 2025).

Edge cases are not a continuum

There are a tiny number of people, mostly with ovotesticular DSD or chromosomal mosaicism, whose sex is genuinely hard to determine. Hard-to-classify cases exist for nearly every biological category — the existence of conjoined twins does not mean "number of people" is a spectrum. A spectrum would require a continuous distribution of intermediate types, each functional in its own right. What actually exists is two functional types and a small number of developmental conditions in which one of those types formed incompletely or atypically. Commenters on /r/detrans often reach for the same analogy:

it's like being born without some fingers, or being born with an extra finger. we don't think that finger number is a spectrum, we all know that humans have 10 fingers. —portaux, desisted

Chromosomes are not the definition either

Trans commenters often point out that some people with XY chromosomes have female-looking bodies, and conclude that "chromosomes don't matter". That is partly right: sex is not defined by karyotype but by reproductive anatomy, which karyotype usually predicts. CAIS shows that chromosomes and appearance can be discordant — not that the body lies between two sexes.

A related claim on trans forums is that a "medically fully transitioned" person has changed three of four sex markers (genitals, secondary characteristics, hormones) and is therefore closer to the other sex than their own (Alice_Oe, trans woman (MTF)). But hormones and surgery alter the appearance of secondary characteristics; they cannot create the gonads or gametes of the other sex. A detransitioned man described how he came to see this:

In reality, HRT or surgery makes you ... a person of your biological sex having undergone HRT or surgery. It doesn't fundamentally change your sex. But this is a hard pill that a lot of trans people can't swallow. I couldn't, and I remember resenting trans women I saw online who would admit they were biologically male. —sydney-speaks, detrans male

Even if sex had intermediates, it would not change much

Finally, suppose some people with DSDs really were neither male nor female. That would describe those individuals; it would say nothing about a person with an ordinary male or female body who feels they should have been the other sex. Using intersex people this way borrows the authority of a physical condition for a claim that is really about identity and feeling.

How intersex is used in gender identity arguments

Several distinct arguments draw on intersex conditions. Separating them helps clarify what each actually claims.

• "Sex is a spectrum, so identity can sit anywhere on it." Addressed above. The premise is false, and the conclusion would not follow from it anyway.
• "Sex is assigned at birth." "Assigned sex" comes from intersex medicine, where doctors did have to choose a sex of rearing for infants with ambiguous genitals. Applied to the 99.98% of babies whose sex is simply observed, it implies an arbitrariness that does not exist — which is why this site does not use AMAB/AFAB ("assigned male/female at birth").
• "Being trans is like an intersex condition of the brain." This frames gender dysphoria as an innate, body-like variation, which makes medical treatment sound like correcting a birth defect. There is no diagnostic test for such a condition (see born in the wrong body).
• "5-ARD shows people can change sex." People with 5-ARD are males whose genitals look female at birth and virilise at puberty. Their sex does not change; their appearance catches up with it.

I've often seen people in the trans community compare it to an "intersex condition of the mind". That's how it gets sold to people who are more critical, including doctors I assume. —femaleprince

Another detransitioned woman pointed out what this framing implies:

If being transgender was a medical condition then you would be testing for it and treating it only in people that you can prove are trans, so no more self-ID. —Odd-Associations, detrans female

Intersex as a personal explanation

For some people, intersex is not just a debating point but a private hypothesis about themselves. Some detransitioners describe having been convinced they must secretly be intersex — "the only way I could explain why I did what I did, liked what I liked" (deleted user) — when the discomfort was actually rooted in gender stereotypes, sexuality or distress.

Some trans-identified people on r/MtF and r/ftm express the same hope; others warn against it. One trans man suggested the search for an intersex diagnosis often stems from "a search for validation of one's own transness" (glitteringfeathers, trans man (FTM)). When a non-binary identity is justified as "biologically intersex", the underlying belief is still that personality ought to match the body — the stereotype the identity was meant to escape.

Sport and law

DSDs also feature in disputes over sport, where some 46,XY athletes with DSDs who went through male puberty have competed in female categories; sports medicine bodies have criticised the International Olympic Committee (IOC) for leaving eligibility rules for trans and DSD athletes to individual federations (Pigozzi et al. 2022). For how legal systems define sex, see sex vs gender in law.

What intersex people say

Intersex people do not speak with one voice, and it would be misleading to suggest otherwise.

Advocates who embrace the spectrum framing

Prominent advocacy organisations such as interACT describe intersex as "an umbrella term for differences in sex traits or reproductive anatomy" and their own glossary states that "intersex is a spectrum" (interACT). Many of these groups align themselves with trans organisations, and some reject the term DSD as medicalising. The Australian group InterAction recently reaffirmed solidarity with trans people while noting that "many people with intersex variations grow up to be transgender or gender diverse (while equally many do not)" (InterAction 2025). Some people with DSDs also identify as trans; one trans man who learned he had XY chromosomes after transitioning described feeling caught between communities (ArcherSeabird, trans man (FTM)).

People with DSDs who object

Other people with DSDs object strongly to being used as evidence for a sex spectrum. Claire Graham, who has MRKH (Mayer-Rokitansky-Küster-Hauser) syndrome, in which the uterus and vagina are absent or underdeveloped, argues that the notion that sex is a spectrum or that DSDs constitute a third sex is both factually incorrect and offensive (Woman's Place UK 2019). On /r/detrans, a woman with a DSD who was also a moderator wrote repeatedly about this:

I am so fed up of people reinforcing the very idea that having a congenital condition of sexual development means you aren't male or female, when in fact it reinforces that there are only two sexes. —DetransIS, detrans intersex female

For her, the spectrum idea was not abstract. She describes how it shaped her own medical history:

The nonsense of "sex being a spectrum" is what destroyed MY life and MY body. The fact that sex is a "spectrum" is what convinced people I could be made male and it allowed me to double down myself doing serious harm through transition. —DetransIS, detrans intersex female

A desisted intersex commenter criticised both sides — gender activists who "romanticize intersex conditions" and conservatives who denounce intersex surgery only as "a rethorical point":

At times I've been told we're 'middle of the roads' that 'get to choose'... No, we get handed a platter of mismatched, incomplete features and disabilities. We don't get to choose shit. —vimefer, desisted

The common thread among these objectors is not a political position but a wish to be seen accurately: as men and women with medical conditions, not as proof of anyone else's theory.

Gender dysphoria in DSD populations

DSDs offer something close to a natural experiment: people whose prenatal hormone exposure, genitals or sex of rearing differ from the norm. Researchers have studied whether these people later develop gender dysphoria or change gender role. The results are important — and frequently misread.

What these findings show

Prenatal androgens matter. Males whose bodies were exposed to and could respond to testosterone before birth (5-ARD, cloacal exstrophy) often reject a female rearing, while males who could not respond to it at all (CAIS) almost never do. This was a decisive blow to the theory, promoted by psychologist John Money, that infants are psychosexually neutral and gender identity can be set by rearing alone (Cohen-Kettenis 2005).

Gender non-conformity is not the same as a cross-sex identity. Girls with classic CAH, exposed to high levels of androgen before birth, are well documented to be more "tomboyish" on average. Yet in Dessens' review almost 95% of those raised as girls grew up comfortable as women. Strongly masculine interests, even when they have a measurable biological cause, overwhelmingly coexist with a female identity. This is consistent with what many detransitioned women say about their own gender non-conformity: being a masculine woman is a way of being a woman.

Context shapes outcomes. Rates of gender role change in 5-ARD vary widely between studies and countries; a large European multicentre study found a much lower rate of around 13% in androgen-synthesis disorders, and clinicians note that culture, religion and local gender norms influence decisions (StatPearls). In communities where males virilise visibly at puberty and male status confers social advantage, living as a man is also the path of least resistance.

The direction is towards sex, not away from it. The most striking "gender changes" in DSD populations are of males who were raised as girls and later chose to live as men — that is, people moving towards their sex after an assignment imposed on them in infancy. These cases are often cited as evidence for an innate gender identity that can diverge from the body. They show something closer to the opposite: that the body's sex, and its prenatal hormonal environment, tend to reassert themselves.

Limits of the evidence

These studies are small, often decades old, drawn from specialist clinics and partly built on case reports. They also cannot be extrapolated to people without DSDs: there is no evidence that the much larger number of young people now presenting to gender clinics have any comparable hormonal or anatomical condition. Claims that trans identity is a "brain intersex" condition remain speculative.

Surgery on intersex infants

The Money era

From the 1950s onwards, standard practice for infants with ambiguous genitals was shaped by John Money at Johns Hopkins. Money believed gender identity was malleable in the first two years of life and that children should be surgically "normalised" early and raised unambiguously as one sex (Money, Hampson & Hampson 1955). Parents were often advised to keep the diagnosis secret, and many intersex adults only learned their medical histories later in life (Human Rights Watch 2017b).

Money's most famous case was not intersex at all. David Reimer, a boy whose penis was destroyed in a botched circumcision, was raised as a girl on Money's advice; Money publicly reported the case as a success while Reimer was rejecting his female identity in childhood (Diamond & Sigmundson 1997). Male infants with cloacal exstrophy were routinely castrated and raised as girls on the same reasoning; Reiner and Gearhart's follow-up found that more than half later identified as male (Reiner & Gearhart 2004).

Resistance and reform

Intersex adults began organising in the 1990s, most visibly through the Intersex Society of North America, against genital surgery performed on infants too young to consent. A 2017 report by Human Rights Watch and interACT documented "medically unnecessary surgeries" that "can inflict permanent harm on intersex children", based on interviews with intersex adults, parents and clinicians (Human Rights Watch 2017a). In 2015 Malta became the first country to prohibit medically unnecessary genital surgery on intersex infants (Reuters 2015).

As someone born intersex and given child surgeries to conform my body to M, I agree. Was it medically necessary to make these changes? No. Was it for my bodily health? no. It was for a culture that can't accept a male body with some female characteristics. —aykana_dbwashmaya, questioning own gender transition

Parallels with gender medicine

Detransitioners and critics of paediatric medical transition often draw a comparison with intersex surgery. The comparison has real force, but it is not exact.

Parallels

• Irreversible interventions before adult consent. Both involve permanent changes to the bodies of children and adolescents, with consequences for fertility and sexual function, before the person can fully understand what will be lost. See puberty blockers and fertility.
• Theory ahead of evidence. Money's model of gender malleability guided practice for decades without good long-term outcome data, and was publicly defended by its leading figure while it was failing. Systematic reviews have since found the evidence base for paediatric transition weak (see evidence reviews).
• Making the body match a gender idea. Both practices assume that a child's psychological wellbeing depends on bringing the body into line with a gender category — in one case, the category doctors chose; in the other, the category the child identifies with.

It's pretty crazy that people view adults deciding to perform surgery on intersex newborns as barbaric, but don't see how letting a literal child decide to mutilate their body or mess with its natural hormonal balance is even more insane. —Mercenarian, desisted female

Disanalogies

• Who wants the intervention. Intersex surgery was imposed on infants who expressed no wish at all. Paediatric transition is usually requested by the young person. That difference is real — though it moves the question to whether a child or adolescent can meaningfully consent to irreversible loss (see informed consent critique).
• A body with a diagnosis vs a body without one. People with DSDs have an identifiable physical condition, and some interventions for them (for example, hormone replacement in salt-wasting CAH, the severe form in which the body cannot retain salt) are clearly medically necessary. In gender dysphoria the body is typically healthy; the intervention alters healthy tissue to treat distress.
• Opposite directions. The intersex movement fights against early intervention; much trans advocacy fights for earlier access. A detransitioned man summarised this tension:

Intersex people just want to be left alone as children with forced surgical treatments and forced gender assignments ...whereas, the trans community wants children to have the ability to have surgical treatments and gender affirming care. —-AnomalousMaterials-, detrans male

The principle the intersex rights movement won — defer irreversible, non-essential interventions until the person can decide for themselves — is the same principle many detransitioners wish had been applied to them. Others caution against turning intersex people into a rhetorical tool in this debate too; one detransitioned woman argued that "it would be an appropriation of intersex issues to constantly compare them to the issues affecting trans identified children" (Downtown-Store-6514, detrans female). Both points can be held at once.

DSDs and detransition

A few people in the detransition community have DSDs. Some describe being pushed toward transition because their bodies or behaviour did not fit expectations of their sex; others describe hormones interacting unpredictably with an undiagnosed condition, or medical records that conflated their DSD with transition. Several commenters argue suspected DSDs should be properly investigated before any transition — a confident "intersex" self-diagnosis and an actual diagnosis are very different things.

Doctors absolutely need to know your sex, there are huge differences between male and female bodies and they don't go away all because you removed a few organs and are taking cross sex hormones. —DetransIS, detrans intersex female

If you are questioning a transition, the support directory lists gender-exploratory therapists and detransition support groups. You can also explore related research in the study archive and personal accounts in the video archive.

Related pages

• Gender identity beliefs
• Sex vs gender in law
• Third gender cultures
• Born in the wrong body
• Gender stereotypes
• Non-binary identities
• Gender non-conformity without labels
• Iatrogenic harm

References

• Blackless, M., Charuvastra, A., Derryck, A., Fausto-Sterling, A., Lauzanne, K., & Lee, E. (2000). How sexually dimorphic are we? Review and synthesis. American Journal of Human Biology, 12(2), 151–166. citation.
• Sax, L. (2002). How common is intersex? A response to Anne Fausto-Sterling. Journal of Sex Research, 39(3), 174–178. PubMed, full text.
• Hughes, I. A., Houk, C., Ahmed, S. F., Lee, P. A., & LWPES/ESPE Consensus Group (2006). Consensus statement on management of intersex disorders. Archives of Disease in Childhood, 91, 554–563. PDF.
• Goymann, W., Brumm, H., & Kappeler, P. M. (2023). Biological sex is binary, even though there is a rainbow of sex roles. BioEssays, 45(2), 2200173. source.
• Wright, C. M. (2025). Why there are exactly two sexes. Archives of Sexual Behavior, 54, 3941–3945. source.
• Dessens, A. B., Slijper, F. M. E., & Drop, S. L. S. (2005). Gender dysphoria and gender change in chromosomal females with congenital adrenal hyperplasia. Archives of Sexual Behavior, 34, 389–397. source.
• Cohen-Kettenis, P. T. (2005). Gender change in 46,XY persons with 5α-reductase-2 deficiency and 17β-hydroxysteroid dehydrogenase-3 deficiency. Archives of Sexual Behavior, 34, 399–410. PubMed.
• Mazur, T. (2005). Gender dysphoria and gender change in androgen insensitivity or micropenis. Archives of Sexual Behavior, 34, 411–421. source.
• Reiner, W. G., & Gearhart, J. P. (2004). Discordant sexual identity in some genetic males with cloacal exstrophy assigned to female sex at birth. New England Journal of Medicine, 350(4), 333–341. source.
• Klinefelter and Turner syndrome prevalence: Klinefelter Syndrome – an overview (ScienceDirect Topics), source; Syndrome de Klinefelter et syndrome de Turner : pour une meilleure prise en charge (2011), source.
• StatPearls. 5α-Reductase Deficiency. source.
• Pigozzi, F., et al. (2022). Joint position statement of FIMS and EFSMA on the IOC framework on fairness, inclusion and nondiscrimination based on gender identity and sex variations. BMJ Open Sport & Exercise Medicine. study page.
• Human Rights Watch & interACT (2017a). "I Want to Be Like Nature Made Me": Medically Unnecessary Surgeries on Intersex Children in the US. source.
• Human Rights Watch (2017b). A Changing Paradigm: US Medical Provider Discomfort with Intersex Care Practices. source.
• Human Rights Watch. Intersex Children (topic page). source.
• interACT. Intersex People Oppose Trump Administration's Narrow Sex and Gender Definitions (2018 talking points). PDF.
• interACT. Intersex Variations Glossary. source.
• InterAction (2025). Better Together 2025: Intersex Voices Leading the Way. source.
• Woman's Place UK (2019). Biological sex is not a spectrum: there are only two sexes in humans. An interview with Claire Graham. source.
• Reuters (2015). Surgery and sterilization scrapped in Malta's benchmark LGBTI law. source.
• Krob, G., Braun, A., & Kuhnle, U. (1994). True hermaphroditism: geographical distribution, clinical findings, chromosomes and gonadal histology. European Journal of Pediatrics, 153(1), 2–10. PubMed.
• Intersex Human Rights Australia. Intersex population figures. source.
• Money, J., Hampson, J. G., & Hampson, J. L. (1955). Hermaphroditism: recommendations concerning assignment of sex, change of sex and psychologic management. Bulletin of the Johns Hopkins Hospital, 97(4), 284–300. PubMed.
• Diamond, M., & Sigmundson, H. K. (1997). Sex reassignment at birth: long-term review and clinical implications. Archives of Pediatrics & Adolescent Medicine, 151(3), 298–304. PubMed.