Colin Wright dismantles Zemenick’s claim that sex isn’t binary

June 8, 2023 • 12:30 pm

A few days ago I criticized an op-ed in the San Francisco Chronicle by Ash Zemenick, a biologist who is self-described as “non-binary.” You can see an archived version of his piece by clicking on the screenshot below:

I later wrote a short letter to the editor, which was published, refuting Zemenick’s idea that sex is not a binary, and reproduced the letter on my site.

But I’m getting tired of trying to correct people about what biologists consider to be the definition of “the sexes,” and it’s a never-ending task because gender activists keep telling people that sex is a “spectrum”—that there are more than two sexes.  Since most people don’t know much biology, they simply buy what the activists say,  a false and ideologically-based claim designed to read the gender spectrum back into nature. If gender is a spectrum, they think (and it is, but a BIMODAL spectrum), then biological sex must be too. I call this the “reverse naturalistic fallacy”: an example of the idea that what is good to humans must be what you see in nature.

But there’s a man more tired than I of this incessant correction, for he’s devoted a lot of his career to questions of sex and gender: biologist Colin Wright, who has a Substack column called “Reality’s Last Stand“.  Like me, when Colin sees such an obviously misguided piece as Zemenick’s, he sighs deeply, thinks a bit, and then and gets to work refuting it.  It’s an onerous and never-ending job, but somebody has to do it! (Other major participants in these corrections are Carole Hooven at Harvard and Emma Hilton at Manchester.)

Wright’s own refutation of Zemenick’s piece, which is far more thorough than mine, was just published at Queer Majority, and you can read it by clicking on the screenshot below. I’m not going to reprise his biological arguments, some of which I’ve made, and I give two more links below to his writings on the sex binary. Rather, I’ll give a couple of excerpts about ideology. Colin’s words are indented:

Why is the binary nature of biological sex being questioned now? And why is emphasizing the truth important?

Over the last decade, we have observed a striking shift in the politics of LGBT issues. There has been a move away from broadly supported principles based on equality toward the imposition of radical, pseudoscientific ideologies concerning biological sex. A growing genre of articles in high-profile news outletsmagazines, and scientific journals is signaling the end of a binary and immutable perspective on biological sex. The appeal of these pieces lies in the belief that rejecting the binary concept of sex provides society with a liberating opportunity for self-definition, unfettered by material constraints.

One might consider these debates too arcane to have any real significance. However, the pseudoscientific notion that biological sex is mutable and exists on a non-binary continuum serves as a key justification for allowing males who identify as women to compete in female sports and access female prisons, and for administering treatments such as puberty blockers and “gender-affirming” (i.e., body modifying) hormones and surgeries to adolescents and adults alike to fix a perceived misalignment between their sex and “gender identity.” The implications are serious, as these recommendations make women’s sex-based rights unenforceable and directly impact the healthy bodies and minds of children. It is of utmost importance that such actions are grounded in reliable science, not in fashionable political ideologies.

This is not, in other words, just an argument about biological facts. Those facts are known; they’ve become “conventional wisdom” among biologists. Instead, the real argument is about who has the power to dictate societal views on gender and gender rights. The ideologues hold the postmodern view that the truth is just what you think is the truth from your own standpoint, and there are not absolute truths. To these people, what’s important is who holds societal power.

Why do activists make huge overestimates of the number of “intersex” people? People keep quoting Anne Fausto-Sterling’s figure, published in 2000, that 1-2% of the population are intersex, even though Fausto-Sterling herself retracted that claim years ago.  This is a prime example of how people keep insisting on “facts” that they know are wrong simply because those “facts” buttress their ideology.  But here are the real data:

Zemenick’s claim that 1-2% of the population has intersex conditions vastly overstates the reality, exceeding the actual figure by nearly 100 times. This statistic originated from Anne Fausto-Sterling in Sexing The Body: Gender Politics And The Construction Of Sexuality (2000), and was reiterated in an American Journal of Human Biology article titled “How Sexually Dimorphic Are We?” Fausto-Sterling and her colleagues reached their 1-2% estimation by applying an arbitrary and excessively broad definition of “intersex” as “an individual who deviates from the Platonic ideal of physical dimorphism at the chromosomal, genital, gonadal, or hormonal levels.” To convey the absurdity of their strict criteria, females with unusually small clitorises and males with unusually large penises were classified as intersex.

Most critically, the vast majority of the people Fausto-Sterling categorized as intersex exhibited no sexual ambiguity whatsoever. When a clinically relevant definition of intersex is applied, such as when “chromosomal sex is inconsistent with phenotypic sex, or in which the phenotype is not classifiable as either male or female,” the incidence of intersex conditions dwindles to approximately 0.018%, or about 1 in 5500. Nevertheless, the prevalence of intersex conditions is immaterial to the binary nature of sex. The occurrence of sexual ambiguity, regardless of its frequency, does not constitute a third sex.

I’ve put the last two sentences in bold because they show that the frequency of intersex individuals has nothing to do with whether or not biological sex is a binary trait.  Somehow, though, the ideologues think it does, and on top of that they keep spouting Fausto-Sterling’s hundred-fold overestimate of the frequency of intersex individuals.

If you want a lucid description of why sex is binary, and about the falsity of using traits other than gametes to define sex, read the piece. I’ll add that Colin has written two other good takes on this problem, which I’ve put below with links:

“Sex Is Not a Spectrum” and

“Understanding the Sex Binary”

35 thoughts on “Colin Wright dismantles Zemenick’s claim that sex isn’t binary

  1. That is a great article, and thanks for drawing it to our attention. I particularly like the final passage:

    “Human rights must be built on a foundation of truth. Hope lies in speaking that truth as loudly as possible and limiting the collateral impact of reality-distorting ideologies on policy, medicine, and society until evidence and reason make their inevitable comeback”.

    1. Ditto. Including Jerry’s mention and explanation of the “reverse naturalistic fallacy”. Thanks to Wright for developing the full story for journal publication AND to Jerry for developing the 200-word precis for the large popular, mass circulation newspaper.

  2. I don’t know the answer to this and have tried to find but without success but do the drugs they give to children differ between sexes. Because if they do the doctors who administer these drugs must have some way of distinguishing what biological sex the person is and therefore biological sex exists. But if it’s the same drug then my question is moot.

    1. It’s a fair question. AFAIK the same class of drugs is given to stop puberty in both males and females (e.g., leuprolide, which is used to treat both male and female diseases like prostate cancer and endometriosis).

      But your question got me thinking: almost all trans kids who don’t conform to a sex stereotype and who go on puberty blockers will eventually go on to take cross-sex hormones to help them conform to the stereotype associated with the other sex. These same gender clinics could do a vastly greater busine$$ by expanding to also provide hormonal treatment for the much larger number of kids who also fail to conform to a narrow sex stereotype but are not trans: geeks, nerds, late bloomers, gamers, theatre kids, 98-pound weaklings. Why should all those other kids be left marginalized and exploited and at risk of suicide over their failure to conform to their own sex stereotype? Why do gender clinics act as gatekeepers and fail to affirm the gender of those poor hapless folx? This is obviously and grossly unfair. There should be gender freedom and free hormone injections for everyone.


      1. Like I tell my wife, I identify as a 6 foot 4, full head of hair, with a BMI of 20 male but she just laughs at me.

        Thanks for the answer.

      2. These same gender clinics could do a vastly greater busine$$ by expanding to also provide hormonal treatment for the much larger number of kids who also fail to conform to a narrow sex stereotype but are not trans: geeks, nerds, late bloomers, gamers, theatre kids, 98-pound weaklings.

        This is a really alarming interview with a surgeon in Portland, Oregon who conducts “gender-affirming” surgical procedures. The level of experimentation is unbelievable, and there are various options depending on how strongly the patient identifies as “non-binary”. Amongst many jaw-dropping moments for me was when he says of the operations that he carries out:

        “I think we’re a little bit different geographically in Portland and on the west coast where I feel like we just have a lot more sort of non-binary queerness fluid identities versus like places like New York seem to be very binary, um, so I think part of it’s geographical […]”.

        And this isn’t some kind of social contagion?!

        1. Geez. There’s an unholy enabling relationship if I ever saw one. The two of them are absolutely loathesome.

        2. They’re discovering untapped market opportunities in Portland where there are so many unfilled needs for gender affirmation. Imagine what they could do if they just realized that ~all teenagers feel uncomfortable in their gender, and need help conforming to a stereotype. I feel like there’s a “Glengarry Glen Ross” movie to be made about this. “Always be transing.”

        3. “Affirmation” is an accurate expression for the over arching objective of queer theory – to transform society to accept true reality – that queer theory purports to find – free of any sexual distinctions of any sort, using the liberated true self that was trapped in the prison of the body.

  3. “…This overlooks the fact that one’s actual ability to produce gametes doesn’t define their sex. A sterile or pre-pubertal male remains male due to the development of male primary reproductive organs, irrespective of their current functionality. Similarly, surgical removal of one’s gonads doesn’t alter a person’s sex, as their reproductive phenotype has already manifested. …As I have pointed out several times, an individual’s sex is defined by the type of gamete they can /or would/ produce.” – Colin Wright

    If individuals with sperm-producing testicles and ones with non-sperm-producing testicles are both male in the same sense of “male”, then having some temporal part (* with testicles (and lacking any temporal part with ovaries) is the only biological attribute which is both necessary and sufficient for being male (only). If you know that somebody has a testicle-equipped (present or past) temporal part, you thereby know that he produces sperm during some life-phase, or if he doesn’t, that he would normally do/have done so.

    (* By speaking of temporal parts of organisms, I’m presupposing four-dimensionalism about them, according to which they are 4D objects or “spacetime worms” having both spatial parts and temporal parts. For example, Colin-Wright-2013 is a one-year-long past temporal part of Colin Wright.)

  4. Someone posted earlier that this was “queering”. I conclude it is. It is not a mistake. It is very straightforward. Analogous to historians debunking The 1619 Project.

    In haste, I give a quote from the podcast linked below (please verify – I’m in the process of getting sources):

    “Queer is by definition whatever is at odds with the normal, the legitimate, and the dominant. There is nothing in particular to which it necessarily refers, it is an identity without an essence.”
    -David M. Halperin

    If anyone can spend the time, James Lindsay makes a strong claim with references that queer theory is the doctrine of a Gnostic-Hermetic cult in this podcast :

    It sounded preposterous but after listening, I think Lindsay has a point.

    1. I was hasty and cannot edit now – a correction:

      Queering is the strategy Zemenick’s piece uses.

      PCC(E), Wright, et. al. debunking the claim is analogous to professional historians debunking specific parts of The 1619 Project.

  5. I wish, just once, the “sex is not binary” people would give us all an example of a naturally occurring reproductive event that was done by more than two sexes.


  6. In reply to Jerry’s original post on the Zemenick article, a commenter noted the wacky DNA sequence included in the graphic at the top of the article. I wasn’t able to see the original article at the time (paywalled) but looked at the version Jerry linked to from the wayback machine today. Holy cow:


    Like headlines I guess the illustrations also were chosen by the Chronicle editors and not by Zemenick. Still embarrassing.

  7. Excellent article.
    Wright rightfully points out that the first thing we have to do to understand what’s at issue is disentangle sex from gender. It’s interesting to see how they both define “gender” then.


    “gender” is usually characterized by notions of masculinity and femininity or the social roles, behaviors, and expressions traditionally linked to sex.


    Here we now refer to sex of the mind, or what I’d like to call cerebral sex. This is one way to think about gender — how we, in our heads, think about ourselves and how we fit into our society and culture

    Notice the way Zemenick fails to mention anything about masculinity or femininity. This is deliberate I think. Under Wright’s definition, a timid, poetic man who works in a flower shop would be a different gender than his brother who drives a forklift and likes rock-climbing. That’s clear, but it’s not necessarily what Zemenic means. The florist might still consider themselves a man and the guy using heavy machinery might identify as transgender.

    So what does he mean? This is not clear, but from what I can tell it seems to come down to the feeling “I like it when I/other people think I’m a woman instead of a man” or maybe just “I don’t like it when I/other people think I’m a man.” No direct references to stereotypes are being made here — which might make it seem like they’re not directly involved. Yet we couldn’t make the distinction we’re making unless we were noticing the distinction society was making. And we couldn’t just “like” it but need it if we didn’t think those distinctions were so damn important and necessary that we must be treated differently.

    From “I hate being thought of and treated like a man” comes “therefore, I’m not one.” If determining who’s male or not male is a hopeless task, then it’s easier to sell that conclusion.

    1. Yep – this is in line with Gnosticism.

      Gnosis – self-knowledge – think New Age, transformation, breaking from the prison of the body, on which society inscribes itself (Judith Butler).

      James Lindsay’s podcast I linked above shows this is not a mistake.

      I’m still trying to absorb the idea, but it seems to make some sense.

    2. Even gender theorists now admit that…

      “‘Gender’ doesn’t pick out any one thing; it equivocates among many.”

      (Briggs, R. A., and B. R. George. /What Even Is Gender?/ New York: Routledge, 2023. p. 5)

      1. This is the strategy – to render distinctions …. irrelevant or incoherent, to release the true self from the prison of the body.

        Judith Butler goes even further out there but I will refrain.

      2. It should be mentioned that Briggs & George aren’t happy about the confusing ambiguity of “gender (identity)”. They want things to be sorted out; and their book is interesting, because they’ve developed a novel gender-theoretic approach, which substitutes the plural term “gender feels” for “gender identity”:

        “We’ve pointed out some costs of the ‘gender identity’ framing – but what’s the alternative? …[W]e propose framing things in terms of gender /feels/: attitudes about one’s relationships to various nonsubjective aspects of our shared material and social reality, which we’ll refer to collectively as /gendered traits/.

        [Gendered] traits (like having a Y chromosome, wearing dresses, or being a man) are properties of people and are not primarily subjective psychological states; someone’s having or lacking a particular gendered trait is part of shared social or material reality. …We’ll divide traits into three buckets, which we’ll call /sexed biology/, /gendered behavior/, and (belonging to) /gender categories/.” (p. 32)

        “A gender feel about a gendered trait is an attitude or disposition about the fact or possibility of one’s possessing that trait.” (p. 38)

        (Briggs, R. A., and B. R. George. /What Even Is Gender?/ New York: Routledge, 2023.)

  8. Wait. “females with unusually small clitorises and males with unusually large penises were classified as intersex”. Is that right or should it be the other way around?

    1. That is what Wright’s article says, with the indicated emphasis. I can’t confirm that the famous Fausto-Sterling article actually did include, as Wright says, men with larger than typical penises and woman with smaller than typical clitorises in their definition of intersex as only the abstract comes up free. But the point is that if anything outside the “platonic ideal” was lumped in, then those individuals would be counted. (How do you even tell if a clitoris is “too small” when the large crura are buried underneath the vulva? What does “too small” even mean if the woman is sexually content?). But he does say that most of the 1.7% did not consider themselves to be intersex, so clearly there is a collision of terms in the Fausto-Sterling paper. Jerry’s coin-toss figure is much closer to the truth.

      1. The URLs for the Fausto-Sterling papers are, This paper (the “Fives Sexes”) the author uncritically quotes John Money and comes up with a 4% statistic (from Money). Money himself rejected the 4% claim. The best known Fausto-Sterling paper can be found at This paper has the now infamous 1.7% (actually 1.728%) statistic.

        One of the amazing things I learned from these papers is that I am an Intersex person. This would come as quite a surprise to my (now deceased) parents.

    2. Hi Mark! Fausto-Sterling’s paper included upper and lower bounds for what constituted a “Platonic ideal” with respect to the length of the clitoris and penis. So any males born with penises over the upper bound (4.5cm), and any females born with clitorises below the lower bound (0.20cm), would be categorized as intersex.

  9. Wright’s is a devastating critique that everyone should read. Either Zemenick’s analysis is just badly flawed or it is purposely designed to confuse. Wright’s patience in dismantling Zemenick’s paper point by point is very much appreciated. It’s just awful that those who care about truth have to spend precious time correcting nonsense.

    I’m glad that Wright went the last step in his article to opine that Zemenick’s aim is to create confusion rather than to elucidate truth. Few would go so far as to ascribe motive, even if motive is obvious. I also credit Queer Majority for publishing his piece.

    1. “Either Zemenick’s analysis is just badly flawed or it is purposely designed to confuse”

      I vote unequivocally for the latter.

  10. PZ Myers definitely has the most ridiculous take on the (lack of) sex binary that I have seen from a biologist:

    Apparently dancing and basket weaving are very important for determining one’s sex, but unfortunately we never get to learn how.

    1. PZ Myers has gone off the rails a long time ago. I used to follow him in my early years as a “New Atheist”, but understood many years ago that this was a waste of time. The way he argue is the same as some post-modernist philosopher argue, That is perhaps some sane thought, but interspersed with complete nonsense and absurdities. I see on his site and his youtube channel that when some people tries to argue for the sex binary. (which is true) , PZ Myers response is usually unconvincing and sometime just plain stupid. Conclusion, just a waste of time to try the follow the way his arguments for this issue

  11. “Nevertheless, the prevalence of intersex conditions is immaterial to the binary nature of sex. The occurrence of sexual ambiguity, regardless of its frequency, does not constitute a third sex.” – Colin Wright

    A very good point! One cannot increase the credence of sexual anti-binarism by increasing the number of intersexuals.

  12. Zemenick doesn’t hide his political agenda. The first thing you read on his “Project Biodiversify” website is “Tools for promoting diversity & inclusivity in biology classrooms.”

  13. “leading to asinine claims about bisexuality being uniquely transphobic” writes Colin Wright. Bisexuality is uniquely transphobic? I thought I had heard of every crazy claim. I guess not.

    1. Bisexuality reinforces a distinction between sexes. Gay or lesbian does too.

      Queer theory antagonizes distinctions such as male or female because its objective is to liberate the true self from the prison of a body which is socially constructed – that is mostly Judith Butler, maybe some Michel Foucault.

      Yes, it sounds preposterous – and I only came to see this today – but read the background. See James Lindsay’s podcast above or his woke translations.

  14. Mitt Castor (of MIT’s Babbling Beaver) has a sly, possibly a little over-the-top piece on what can soon be expected as a result of the current fad for extreme Trans rubbish:
    “ .

    1. Maybe over the top, but this is pretty apt: critical theory as “ideological gain-of-function research.”

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