Sabine Hossenfelder on the transgender phenomenon

April 30, 2023 • 10:00 am

Here physicist Sabine Hossenfelder turns her attention away from physics towards a far more incendiary topic: gender transitions. In this 27-minute video (the last 1.5 minutes is a commercial) she covers the topics below, concentrating on published data to draw her conclusions. In general it’s a good introduction to the issue, and certainly not “transphobic”.

If you haven’t kept up on the issues like the recent determination in some countries that hormone blockers should be considered an experimental clinical procedure rather than a routine treatment), it’s edifying to watch the video. As a physicist, she’s particularly attuned not just to statistically significant effects, but large effects with high statistical significance. We don’t see that in many studies on the effects of affirmative care, puberty blockers, transitioning, and so on, and she is right that sample sizes are quite low and studies generally over too short a period.

I am distilling Hossenfelder’s conclusions below, inserting my own take only when necessary (I make it clear when I do).

a.) What makes a male versus a female? Although she implicitly complains that there are two sexes (and some rare intersexes), she relies on a chromosome-based sex definition rather than one based on gamete size. (She is correct that XXs are usually females and XYs males, but this is not always the case due to chromosome-related “disorders of sex determination”; and at any rate, she should use the definition adopted by biologists who actually deal with sex in plants and animals.)

b.)  What is gender and gender dysphoria? Unfortunately, as per some trans activists, Hossenfelder uses sex and gender interchangeably, and adopts the term “assigned gender at birth” for the entire video.  But genders aren’t “assigned” at birth; rather, biological sex is RECOGNIZED at birth (usually by its correlates).  The phrase is thus doubly confusing. This is my quibble; I have no objection to the rest of her discussion, which is short.

c.)  How hard is it to be transgender? Hossenfelder describes the stigmatization of transgender people throughout the world (it’s illegal in some places), the higher rate of sexual violence they experience, and their higher risk of suicide (she doesn’t mention that the latter may be a correlate of gender dysphoria, which itself could result from general mental problems, rather than suicide being actually caused by a person identifying as a member of one’s nonbiological sex.

d.)  Is the recent rise in the proportion of transgender people due at all to social contagion? The rise is quite dramatic in the US and UK where we have decent data: in some place a doubling or tripling in the last five years. It’s also seen in Sweden, Canada, and other places that keep records. She notes that most of the increase comes from gender dysphoria in young biological women (a reversal of the situation in past years). Hossenfelder notes that social contagion is at least a plausible hypothesis because far more adolescent girls than adolescent boys have mental health issues, which could lead to gender dysphoria. But there are no solid data implicating social causation, says Hossenfelder, nor conclusive evidence for the syndrome of “rapid onset gender dysphoria” said to be prompted by social contagion (i.e., people being prompted to identify as trans due to social pressure or a desire to conform).

e.)  What about gender affirming care and puberty blockers? (These are associated, of course, because part of gender-affirming care is a readiness to prescribe puberty blocks to children with gender dysphoria.) Hossenfelder notes that the touted “perfect safety” of puberty blockers is dubious. Although they do stop puberty, they also have some noxious side effects. More important, there are not enough long-term studies of the medical effects of taking puberty blockers, but the data we have suggest that bone density doesn’t recover after stopping them, and they may be associated with heart problems and infertility.There’s also no strong evidence that taking puberty blockers improves the mental health of the children taking them.

f.) Is hormone therapy efficacious or dangerous? Yes, it does change secondary sex characteristics, but is neither completely reversible nor efficacious in completely eliminating sex-based differences in some traits, even if discontinued.  However, hormone therapy does seem to increase life satisfaction and reduce depression, but the changes are small and some of the studies lack control groups or placebo-effect treatments. Further, the studies haven’t been long-term studies, sample sizes have been small, and hormones like testosterone may reduce depression in biological males themselves, not just in trans males, so it may be a general and not transgender-specific effect.  In some of these conclusions Hossenfelder relies on critiques by Jesse Singal.

Her conclusion are summarized in this chart:

Here general take, as you see, is one of caution towards both the physical and psychological effects of transitioning. We don’t know whether the rise in gender dysphoria and transitioning is due to social conditioning, a new freedom to be yourself, or both. As she says, “Anyone who insists that one of those possibilities doesn’t exist is pushing an agenda, and shouldn’t be taken seriously.”  The fact that we can’t separate those two causes explains why countries like Sweden, the UK, and Finland are placing hormone blockers in the category of an experimental treatment.

h/t: smipowell

41 thoughts on “Sabine Hossenfelder on the transgender phenomenon

  1. Thanks for this analysis –

    New thoughts from me :

    It seems to say something, the ages interested in whatever this is new phenomena is called. Does it get the participants attention? Is there a problem being solved – and what, precisely, is that problem?

  2. There is much reason (even if there are no solid data) to suspect a kind of social contagion at work, as well as TikTok’s undeniable influence in the perpetuation of fads and fashions amongst the young, who are subjected to additional pressure in school and by celebrities not to be, in any manner whatsoever, guilty of “transphobia”.

  3. Some children, particularly at early ages, like to imagine themselves being cats, dogs, or other lovable animals, and display their choice by making appropriate animal noises. I have established a foundation to help empower such children in their new identities. The program, which we call affirmative affirmation, provides psychological affirmation, instruction about the animal of choice, imitation fur, and such physical interventions as may seem appropriate. Contributions to the foundation can be sent directly to me, preferably in cash. We accept $ and £, but no Swedish or Finnish currency.

  4. Just some comments about particular points made.
    c): On the difficulty of being in the trans gender spectrum: I don’t think we can rule out that just being on that spectrum is in itself very challenging, and maybe it does associate with other problems that also can lead to suicide. But I would expect that the main reasons for suicide, self-harm, depression, obesity, and the like is thru both stigmatization from others, and from ones’ own non-acceptance that you are and will always be obviously different.
    That comes across as an unfounded claim on my part, but isn’t it true that effective medical intervention and support for people who on the spectrum is associated with better psychological outcomes?
    Gender dysphoria is not like other dysphorias like anorexia. An anorexic that is allowed to become skeletally thin still thinks they are grossly obese, and they still continue to starve themselves. But a person claiming to be trans can show considerable gains in mental health once they go thru the procedures that they desperately want.
    d): Is there a social contagion aspect to the rise in claimants for gender dysphoria? This too cannot be understood right now. But I had read both here and elsewhere mention that “many” young people who claim themselves to be on the spectrum in fact never act on that aspect of themselves. They live the cis and straight life. But I don’t know if that is really true or what it really means.

    1. Mark, if you listened to Hossenfelder’s video, then you know that, at present, strong claims for the psychological benefits of transitioning cannot be supported with good-quality evidence. (All we hear in the North American mainstream media is that sooo many American medical associations support affirmative care. This is highly misleading. Also, health authorities in Sweden, Finland, Norway, and England have characterized the treatments at issue as experimental, and have restricted access to them. I’d like to read an article about that in the New York Times! Though, the Times, since it hit peak woke about 1 year ago, has done some real journalism on this whole issue.)
      Hence the answer to your question

      “isn’t it true that effective medical intervention and support for people who on the spectrum is associated with better psychological outcomes?”

      is “We don’t know.”
      You write that [emphasis added by me]:

      “a person claiming to be trans can show considerable gains in mental health once they go thru the procedures that they desperately want.”

      This might well be true, but if good-quality studies of puberty blockers and cross-sex hormones show only small positive average effects on psychological well-being, then there must be individuals whose psychological well-being takes a considerable negative hit from these medical interventions. This simply follows from the definition of the mathematical average: If the average effect is zero, but some people experience considerable positive effects than some other people must experience considerable negative effects.
      An example of a person who suffered considerable negative effects from these treatments is Keira Bell:

      Keira Bell: My Story. April 7, 2021
      As a teen, she transitioned to male but came to regret it. Here’s how it felt to enter history in the trans debate.

      And there are many people like Keira Bell. See, for instance, here:

      Detrans Awareness Day Panel Discussion With Detransitioners For Affirmation Generation Documentary. April 2023, 43 mins
      Watch the documentary Affirmation Generation: The Lies of Transgender Medicine. 2023, 91 mins, here:

      1. The Subreddit also is full of
        personal reports from detransitioners, many of them very tragic cases.

        Of course, that doesn’t tell us anything about their real numbers, but even if many of the 46.8k members of that sub may not be detransitioners themselves , but rather interested onlookers, we can assume a significant enough number to remain vigilant about Affirmative Care.

      2. “I’d like to read an article about that in the New York Times! Though, the Times, since it hit peak woke about 1 year ago, has done some real journalism on this whole issue.”

        Translation – “..Though, the Times, since it hit peak alertness to racial prejudice and discrimination about a year ago, has done some real journalism on this totally non-related issue”

  5. Dr. Hossenfelder certainly is popular and prolific on U-Tube. But as we’ve seen in many other cases, a person who is an expert in one field is not automatically an expert of all fields. Hence her errors on sex versus gender, etc. I wish that academics with the ambition to wander out of their lane would have other experts check their terminology before they publish!

    So I asked Chat GTP “What is sex and what is gender?” and it did slightly better than Dr. Hossenfelder, but it too struggled a bit:
    “Sex and gender are two related but distinct concepts [that is one place where it was better]. Sex refers to biological characteristics such as genitalia, chromosomes, hormones, and reproductive organs that typically categorize individuals as male, female, or intersex. These characteristics are generally considered to be determined at birth.” [that is where it did not do so well].

    [But I don’t see a problem with gender, which it goes to next]:
    “Gender, on the other hand, refers to the social and cultural expectations, roles, behaviors, and identities that are associated with being male, female, or non-binary. Gender is not necessarily determined by biological sex and can vary across different cultures and societies.

    While sex and gender are often thought of as binary (male or female), it’s important to recognize that there is a spectrum of biological and gender identities, and that individuals may identify as gender non-conforming, non-binary, or transgender.

    It’s also important to note that gender identity is not the same as sexual orientation, which refers to a person’s emotional and physical attraction to others. Sexual orientation is separate from gender identity and can include heterosexual, homosexual, bisexual, pansexual, and asexual orientations, among others.”

    1. Given that definition of “gender,” a gender identity would be where each person places themselves on their self-assessed scale of masculinity and femininity formed according to their culture.

      1. “…according to their culture.” That’s correct and also impossible to figure out. I’ve been watching the Netflix series Narco about Escobar and the bandits’ favorite dis is “fag”. Obviously created by their culture of machismo. It’s such an intricate pancake…and to be honest, exhausting.

    2. Mark, you wrote that
      “there is a spectrum of biological and gender identities”
      “Dr. Hossenfelder certainly is popular and prolific on U-Tube. But as we’ve seen in many other cases, a person who is an expert in one field is not automatically an expert of all fields. Hence her errors on sex versus gender, etc. I wish that academics with the ambition to wander out of their lane would have other experts check their terminology before they publish!”
      My questions for you: Are you a biologist? If yes, are you claiming that biological sex is a spectrum? If so, why?
      I’m not a biologist, but recently I checked the definition of sex in three recently published dictionaries of biology. The definition given was the same in all three: sex is defined by gamete size, and it is binary because there are only two gametes. And no talk whatsoever of “sex is a spectrum.”
      The dictionaries I checked:
      A Dictionary of Biology. 8 edition, edited by Robert Hine, Oxford University P, 2019 (formerly known as the Oxford Dictionary of Biology)
      Henderson’s dictionary of biology. 16th edition, edited by Eleanor Lawrence, Pearson Education, 2016
      The Penguin dictionary of human biology. by Michael Thain, Penguin, 2009

      So I’m at a loss when it comes to understanding your “there is a spectrum of biological and gender identities.” I understand that there is a spectrum of gender identities, but a spectrum of biological identities? (I’m bringing this up because you quibble with the fact that Hossenfelder isn’t a biologist.)

    3. “a spectrum of biological identities”? In a word, no, Only two sexes have been found in human and their is no spectrum. Human biological sex is quite binary. Human height, weight, IQ, etc. is on a spectrum. Sex is not.

      1. There, not their. Quite binary? You mean just “is” binary? Binary can’t be quite. Binary has 2 options, in this case it either is or it isn’t. That’s the whole point of something being binary, no?

  6. There is an interesting correlation between gender dysphoria and autism. I wonder whether this could be a different situation where the feeling of difference in autism is internally correlated with gender. It’s an area where more research is needed, from what I have found.

  7. Hossenfelder may have concluded that the existence of ROGD is undetermined, but there are some approaches to the topic I didn’t see her mention. A recent article by Kay S. Hymowitz in City Journal on trans and social fads persuasively argues that the theory that there is social contagion in this area fits what we already know about child and adolescent psychology.

    Children are not little adults. The view that kids and teens have an unprecedented, almost mystical certainty concerning “who they really are” when it comes to something complex like gender has never been supported by the consensus of experts in the field of child development. As for ROGD, she writes

    Aside from the otherwise inexplicable queue of girls at gender clinics, the obvious point in ROGD’s favor is that it is consistent with what we already know about teenagers, whereas the idea of adolescent intuitive wisdom is most decidedly not… Gender identity, with its vision of autonomous children in touch with their innermost authentic desires, negates all we know about adolescence, just as it does early childhood

    According to Hymowitz, another problem is that the literature on ROGD seldom takes the enormous amount of time teenagers spend on social media into account. Young people questioning their gender online run into a Petrie dish of all the elements for social contagion, as well as all the mechanisms that back up a placebo effect when Gender Affirming treatments are eventually tried. The studies and statistics are crucial, but so I think is having a background understanding of the different psychology of children and their particular susceptibility to suggestive influence.

    1. We know what can kids do when they don’t get what they want.

      But what can they easily do to terrify their parents in that regard?

      Threaten or act on self harm.

  8. Why is the demo shifting to teen girls, overwhelmingly? And with sudden onset?

    The world destroyed the unbalanced “deal.” Woman were told it was wrong to shelter in the protection of a good man — and that they did not need to do so. And that it was insulting, patriarchal, and fascist to think they needed to. This is called “women’s liberation.”

    So now women have to face the harsh battlefield of physical protection and wealth-creation swimming in the same pool (sick irony) as he-men. Evolution did not select for that over 6,000,000 years of our Genus. How could women possibly possess the fitness traits for that role?

    And men, having a large part of their evolved mission demonized and obliterated, yet not deprived of the ‘reward’ of sex … is it any wonder they become “players?”

    Is it any wonder there is a swelling in the teen girl population of “Gee, I’d be a lot better off and less fearful if I were a man.”

  9. I think Abigail Shrier pointed it out clearly: sudden onset gender dysphoria (SOGD) has little to do with actual gender dysphoria, but more with pubescent girls being unhappy with their bodily changes. I think her comparison to ‘Anorexia nervosa’ is pretty apt. Anorexia nervosa has plummeted, but SOGD has been skyrocketing.
    As an added benefit ‘trans’ allows for ‘victim status’. All this about the epidemic of girls wanting to be men.
    On the other side, I think it is more murky, a chance for omega males to access and rape females, or just cheating in women’s sports.
    I have some sympathy with the former (girls ‘transitioning’ to males), with but none with the latter.

  10. As far as Sabine stepping out of her lane, she is no different than but perhaps more reliable than everyone else and their uncles who proclaim definitively on this issue. For example, here are quotations from George Takei’s Substack on April 28, with both he and Charlotte Clymer, a trans woman, in the byline:
    “Contrary to the vile propaganda spread by anti-LGBTQ extremists, the effects of puberty blockers are reversible. If an adolescent ceases using them, the effects of puberty proceed without issue.”
    “I’m not a medical provider. You should not take blind faith in me when it comes to medical issues. Instead, you should ask medical experts, and on this, they are abundantly clear: gender-affirming care is aligned with best medical practices.”
    “But here’s the best reason to support gender affirming care: we know beyond any shadow of a doubt that it is lifesaving.”

    I’m a fan of Takei, and I understand his motivation in publishing this, to wit, counteracting the vitriol coming from the Right. Still, despite her disclaimer that she is not a medical professional, Clymer makes strong, ostensibly indisputable claims without any citations backing them up. (The link to the JAMA study didn’t work for me; I did find a likely candidate, but its conclusions are far from the bulletproof backup Clymer implies. Whatever criticisms we can level at Sabine, her point that we need more well-designed experimentation yielding more reliable data is spot on.

    1. Stephen, Takei and Clymer are wrong when claiming that puberty blockers are reversible, or they know the truth and try to mislead their readers.
      Takei and Clymer are right when they say “the effects of puberty blockers are reversible. If an adolescent ceases using them, the effects of puberty proceed without issue.” But do adolescents who go on blockers cease using them? No, almost nobody does, according to the existing studies. Hence, the idea that puberty blockers are reversible, a pause button, is likely wrong. If you go on them, you will very likely go on to take cross-sex hormones later – and their effects are irreversible. Hossenfelder gets this right, to her credit.
      Anytime you hear that puberty blockers are reversible you are in the presence of a person who either knows little about the topic or who wants to mislead you.

      1. Puberty blockers — which induce an abnormal, pathological state of hypogonadotropic hypogonadism — are also associated with decreased bone density and cognitive impairment. They’re not only powerful drugs, but stop a significant maturational phase with numerous effects across the body, physical and mental. Playing around with human puberty like it’s a video game with a pause button is foolhardy.

      2. Takei and Clymer are right when they say “the effects of puberty blockers are reversible. If an adolescent ceases using them, the effects of puberty proceed without issue.”

        Are you sure about that? If so, can you give a citation (genuine question)?

        It may be true that, if they desist early enough in puberty, that puberty then proceeds without issue, but I’m highly dubious that this is true if they desist in later puberty. (Though I really am open to correction here.)

        [As I understand it, the claim of “reversible” comes from the use of blockers for precocious puberty, a condition where a child starts puberty abnormally early, around age 9, and they are then put on blockers until age 12 or so, and if they stop the blockers at age 12, then puberty proceeds normally. I’m highly dubious that the same applies if they halt blockers at 14 or 15 or 16 or whatever.]

    2. Okay, so Takei and Clymer write: “But here’s the best reason to support gender affirming care: we know beyond any shadow of a doubt that it is lifesaving.”
      This is false. We do not know whether gender affirming care is life-saving. Health authorities in Sweden, Finland, Norway, and England have characterized the treatments at issue as experimental (basing this on fairly rigorous reviews of the evidence, unlike the American Academy of Pediatrics and all the American medical associations who simply followed its lead), and have restricted access to them.
      The evidence base for these treatments is slim and of poor quality. Hossenfelder is 100% right about this.
      It’s hard to believe how poor highly touted studies on this issue are. For those who want to know the details, I strongly recommend two deep dives Jesse Singal has done (access to both is free), into two studies that Hossenfelder mentions:

      Jesse Singal: Researchers Found Puberty Blockers And Hormones Didn’t Improve Trans Kids’ Mental Health At Their Clinic. Then They Published A Study Claiming The Opposite. April 6, 2022

      Jesse Singal: On Scientific Transparency, Researcher Degrees Of Freedom, And That NEJM Study On Youth Gender Medicine. Jan 31, 2023
      There are a lot of unanswered questions here, which is unfortunate

      Jesse Singal: The New, Highly Touted Study On Hormones For Transgender Teens Doesn’t Really Tell Us Much Of Anything. Feb 7, 2023
      If you take a closer look, you’ll see that the hyped-up headlines are unwarranted

  11. The point about no data to support or refute a social contagion hypothesis strikes me as the kind of study that would be nearly impossible to pursue in today’s climate of self-censorship. I can imagine it being quite difficult for an enterprising researcher to even get funding for this type of work, given the power of the gender activists. Yet, we have many examples of young girls getting caught up in manias of all sorts. Beatlemania, Elvis, Sinatra, fashion fads, etc. Boys fall into fads, too, of course. A good sociologist could begin by cataloging social trends of all sorts and ask which demographic groups and age cohorts are most frequently associated such trends. Something interesting would pop out.

  12. While I (a biologist) stand fully behind the binary sex, I think that in the current situation, the non-binary gender concept may have certain benefits. Any confused teen caught in the social contagion or pushed by adult groomers to transition should just say that s/he is non-binary. This must nip in the bud all offers of chest binders, puberty blockers, opposite-sex hormones, surgeries etc.

  13. Below are a couple of definitions courtesy of NPR, who received them from GLAAD, which touts itself as the world’s largest LGBT media advocacy organization:

    Gender is often defined as a social construct of norms, behaviors and roles that varies between societies and over time. Gender is often categorized as male, female or nonbinary.

    Gender identity is one’s own internal sense of self and their gender, whether that is man, woman, neither or both. Unlike gender expression, gender identity is not outwardly visible to others.

    Set aside for now the (intentional) conflation of sex and gender in the first definition. It is inescapable from these definitions that one must first define “man” and “woman” in order to know one’s gender identity. Let’s substitute “boy” and “girl”. How do we help these kids choose who they are, since nobody, it is said, can know but the child itself? We must start by defining “boy” and “girl”. And, as many here have noted, this is stereotypes all the way down. The child is left to assume that his “internal sense of self” corresponds with “ugh, that’s gross, this sugar and spice and all that’s nice. Give me the toads and snails and puppy-dog tails. I’m a boy!” Then the (intentional) conflation of sex and gender can lead one to this: if you are a boy, then it might be best to also be male—at least to the degree surgery and medication can make you appear so.

    But what of those of us who were deprived when we were young of these grand lessons in identity? We know that there is no determined rule that “men don’t cry in public” or that “a woman wants babies”. We know that men and women can—and do—wear whatever clothes they choose. That they can be in whatever profession their talents, interests, and opportunities lead them to. We know that the stereotypes have grounds in actual behavior, some aspects might even have grounds in biology, but we assert that the stereotypes do not define a given man or woman. And consider: the GLAAD definition states that the social construct of gender “varies between societies and over time”. In theory, this would mean that a given set of roles and behaviors of a “man” in one time and place could identify a person with the same roles and behaviors in a different time and place as a “woman”. Even over a person’s long life, the societal expectations could change significantly: without changing my behaviors and roles at all, I could thus potentially be a young man and later an old woman—or maybe something in between. So much for an “internal sense of self” when it is predicated on a social construct.

    Set aside this potential for flux and confusion (fluidity?). Some of us may wonder what it even means to have an “internal sense of self” that corresponds with such stereotypes. I am a man, but I haven’t the slightest idea what it means to “feel like a man”. I feel like me: I have no way of knowing if that is what “man” feels like to you. But “male” is what I was apparently “assigned” at birth; “man” is what society hoisted on me. Dammit. I want to choose. Why should kids have all the fun?! So, tell me please, anyone: given that I reject any definition of “man” and “woman” in terms of stereotypes, how do I go about choosing or identifying whether I am “a man, woman, neither or both”? How do I know my “gender”?

    1. “Gender is often defined as a social construct of norms …”

      So do we need to walk around the town getting individuals from our local society to check boxes and put their signatures on a form to find out what we are, and then :

      “Gender identity is one’s own internal sense of self and their gender …”

      I agree – it is not at all obvious what “the self” is – let alone how anyone knows its connection to gender.

      And I find the phrase “social construct” peculiar – straight out of post modernism :

      “Social Justice Theory holds that knowledge is socially constructed within a particular culture”

      Source :

      “In the Theory of Critical Social Justice, gender is ultimately socially constructed and, following the queer Theory of Judith Butler, performative ”

      “Within Social Justice, the point of labeling something a social construction is to make it malleable. ”

      Long comment over! Sorry! Too interesting.

    2. My (long=bad form) comment disappeared, so I add – regarding the common plea of “social construct” :

      “So, in the technical, banal (if not vapid) sense, knowledge is a social construction, but in the more profound and meaningful sense of how people use the term, it is not. This trick is one that Social Justice turns upon over and over again.”

      Source : James Lindsay :

  14. I have chatted with a chimeric person who underwent a hormone shift and change in sex identity as an adult. I suspect this is rare, but maybe it isn’t as rare as we think. Maybe intersex can occur without any obvious outward signs.

  15. I get that real Biologists use gametes to determine sex. However, do you get a different result (with a few exceptions, see below) if you use chromosomes (46,XY vs. 46,XY) instead? I understand that rare chromosome anomalies arise (for example, 47,XXY, Klinefelter syndrome). However, if a person has a ‘Y’, they are male, otherwise they are female. Note that 47,XXY is typically never detected.

    Persons who are externally intersex do exist. However, they do have a sex. They are (with rare exceptions) male or female.

    The (very, very rare) exception is mosaics. Apparently, some people have both types of cells in the same human body. Some cells are 46-XX and some cells are 46-XY. Obviously, chromosomes can not be used to determine sex in such cases. Another very rare exception are CAIS persons. These persons are 46-XY males. However, they don’t response to male hormones because of a genetic defect. They look like standard females (typically, they look very feminine). However, they have no female anatomy (uterus) and can not have children. Are they male or female? In my opinion, that is a philosophic question, not a scientific one.

    Do we have any cases of 46-XX who were not female? None that I know of. DSDs do (rarely) occur. I have seen a claim that 1:1000 babies are born with ambiguous genitalia. I have also seen a claim that that the actual proportion may be as low as 1:5000. However, ambiguous genitalia does not mean ambiguous sex.

    Biological sex is observed (or recognized) at birth. Birth determinations are around 99.9% (but not 100.0%) accurate. For example, Caster Semenya was thought to be female at birth. He is actually a 46,XY male with a DSD. In a village in the Dominican Republic, there are ‘güevedoces’. These are males, who appear to be female at birth, but only grow male genitalia at puberty.

    1. I’m inclined to agree, Frank, and I was going to make the same point with SH’s video. The advantage of X and Y chromosomes for lay people is it builds on a story that they learn as kids in school. It also gets around the objection that people are “more than their gametes” even though from an evolutionary view we aren’t. Our bodies are the vehicles designed by natural selection to get the fittest gametes together. But people don’t think of themselves as fruiting bodies, especially if they don’t plan on having children ever, or if they spend their early years taking piano lessons and desperately avoiding intimate contact with opposite-sex gamete producers. We don’t have a problem compartmentalizing this but I think lay people do. And trans people can reject being made prisoner to these tiny little invisible gametes and think they have scored a debating point.

      The other advantage of the chromosome story is that it gets the chronology right if you were explaining it to a child who was ready: “When you were conceived, a sperm carrying a Y chromosome united with a egg which contains always an X chromosome and you developed into a baby boy. If your father’s sperm had contained an X chromosome you would have been a girl. We can talk about meiosis later. Your body inside and out is the way it is because of that XY union. Eventually (at puberty) you (because you are XY) will start to make mature small motile gametes called sperm which can contain either an X or a Y chromosome, along with other changes in your body that are also dictated your Y chromosome. For girls (because they are XX)….etc. The thing (XX vs XY) that dictated how your body is built and what causes us to call you a boy or a girl is the same thing that dictates what kind of gametes you will make. All these things were committed at fertilization and will not change for the rest of your life.”

      So even though gametes define sex absolutely and unambiguously, the chromosome complement of the zygote predicts sex with a high degree of reliability, long before any gamete-producing tissue has developed. This is easily good enough for people in ordinary life. I agree the exceptions you mention are of medical importance and not for people whose children aren’t affected with them. Ordinary people would be more likely to notice that the neighbour’s kid had a cleft lip than that she was intersex or he had XXY.

      If the trans activists claimed that any of this had bearing on the nature of transgenderism then we would have to unpack it all and fall back to our absolute last redoubt of gametic sex. But we don’t, because they don’t. Even trans people accept that XX and XY predict what sex almost everyone will be “assigned” at birth. Their claims about gender are not based in the definition of sex. Rather that they think they have the wrong one. The trans person is not/i> saying, well, I had a penis at birth and still have one but I suspect I’m really XX, and that’s why you must regard me as a woman in every respect because I am. He knows perfectly well that he’s XY. He’s making the entirely different claim that because he has changed his gender identification he is now a woman. The XY fact just doesn’t matter to him. Proving that his gametes are typical sperm wouldn’t change anything.

  16. I am inclined to (strongly) agree. A typical college-educated person has heard of chromosomes, sperm, and eggs (as in female ova). Has the typical college-educated person heard of gametes? Almost certainly not. To put this in perspective, I learned about chromosomes, sperm, and eggs in grade school. However, even 10 years go (perhaps 5, perhaps less) the word gamete would have gone over my head. My guess is that a typical PhD in Physics doesn’t know what a gamete is. My guess is that a typical Biology PhD does know what a gamete is. Google gets 28,900,000 gets hits for ‘gamete’, 507,000,000 hits for ova, and 580,000,000 hits for sperm.

    Your statement that “Even trans people accept that XX and XY predict what sex almost everyone will be “assigned” at birth” turns out to be wrong (at least in some cases). Type ‘biological sex does not exist’ into Google. The very first hit is titled ‘The Myth Of Biological Sex’. You would be amazed at how widespread this belief is. Crazy ideas have a long (if dubious) history. For example, Lysenko had many followers. These days we have ‘flat earthers’ who deny that the planet is round. We even have supposed scientists who state that ‘the periodic chart is colonialist’.

    Even more widespread is the idea that ‘sex is a spectrum’. This is a key idea of the ‘woke’, even if it is not true. It turns out that a person by name of Claire Ainsworth is (partially) responsible for this fallacy. She was the author of an article in Scientific American titled ‘Sex Redefined: The Idea of 2 Sexes Is Overly Simplistic’. I do know that writers don’t always get to choose the titles for their articles. Note that she (apparently) doesn’t believe any of this. Check out She wrote (Tweeted) ‘No, not at all. Two sexes, with a continuum of variation in anatomy/physiology.’ That statement is at least much closer to the truth. She also wrote for Nature ‘Sex Redefined’.

    ‘Ordinary people would be more likely to notice that the neighbour’s kid had a cleft lip than that she was intersex or he had XXY’. Aside from the fact that 47,XXY is not detected in many (75% according to one reference) cases, let us hope you would be more likely to notice a cleft lip than an intersex condition. Observing an intersex condition would require the child to disrobe which would be highly inappropriate.

    I would ask again, do we have any 46,XX persons who produce small gametes? CAIS persons don’t qualify because they are (typically) 46,XY. Mosaic persons don’t qualify because they have cells that are not 46,XX.

    1. >Your statement that “Even trans people accept that XX and XY predict what sex almost everyone will be “assigned” at birth” turns out to be wrong

      I was afraid as I was typing it that it was going to turn out to be wrong. I admit that I have never typed the sentence “biologic sex does not exist”, nor have I typed “the earth is flat and is supported by a giant turtle”. I think there is a Sci Am article that Jerry is going to review claiming the same. It makes me depressed. My understanding is yes, that the title, 2 Sexes is Overly Simplistic is not at all what that article said so perhaps all is not lost.

      In my little homily about reproduction, I was using our “big words” to stand in for what I would actually say to teach a person who hadn’t heard of gametes. Sperm and egg and then say that they are the two types of gametes, that sort of thing. If I hadn’t mentioned gametes in the post all hell would have broken loose. 🙂

      My point about the kid with intersex is that there would be nothing outward to suggest the child was “different” in appropriate casual observing of physical appearance or behaviour….unless she started winning the 800 metres.

      As for 46,XX people with small gametes, I say No, because you need several genes on an intact Y chromosome to make male germ cells. There are 46,XX with male-type genitalia. Some are SRY+ where the SRY translocated onto the X chromosome during paternal meiosis, others SRY- with unclear mechanism — discussed in the linked article. If the father contributed an SRY+ X chromosome, the male genitalia can develop (more or less) but germ cells can’t.

  17. Huge debate on Twitter, many saying that since she is a physicist not a biologist she should shut up. Ironically, most saying that are not biologists yet go on and on telling biologists the usual woke tropes concerning sex and gender.

    “I saw the best minds of my generation destroyed by madness.”

    TRAs are more and more like flat-earthers, young-earth creationists, and astrologers, but with the difference that their woo actually impacts others.

    It would be interesting to see whether Sabine responded (if she has), but I can’t since she’s blocked me on Twitter because we disagree about physics. (We both have doctorates in physics.) Like Jerry I mostly agree with her here, but she might not be the best voice since she is (perhaps unintentionally) easily angered and seems more interested in stating what she believes (in many cases, far from the consensus in physics) than in reasonable debate about it.

  18. Blocked because of a disagreement about physics? That’s somewhat amazing. I can not imagine taking any topic in physics that seriously. Of course, I don’t have a degree in physics. I do have a degree in chemistry and I can not imagine taking any topic in chemistry that seriously.

    1. We’d disagreed before, but that is par for the course. It might not be clear to non-physicist that she is not a “famous physicist” and that some of her opinions on physics are non-mainstream. Regarding controversial topics, she has often claimed that because she wrote a blog post about it in 2015 or whatever that the matter is settled and people who ignore that are stupid. “Sabine wrote it. i believe it. That settles it.”. That is not the way science works.

      Recently, she complained about people writing papers and not citing her own work, implying that if they had been aware of her own work then there would have been no need to write a new paper. I pointed out that she had written a paper on a topic which didn’t cite my own work on it. Then she blocked me. (She was certainly aware of my papers on that topic since they had been discussed extensively on her blog, including by her.)

      With regard to her recent video, of course the truth of a statement is independent of the speaker’s qualifcations or the manner in which the statement is made. Many of the woke said that what her recent video on the trans fad must be wrong because she has no qualifications in that area. But, of course, the same people don’t believe biologists who do have qualifications in that area.

      1. Just to be clear, while one should of course cite the relevant literature, sometimes one misses something. No big deal. (Usually, when pointed out, authors will add the reference is there is still time.) It sometimes makes sense to not cite papers one is aware of, for example if a) it is clear that they are wrong and b) they are widely perceived to be wrong and/or relatively unknown. But to complain about people not citing her papers, then get riled up when I point out that she is guilty of the same thing, and then to block me for pointing it out, is not the way civil discussion should work.

        As I’ve pointed out in other contexts, those who refuse to discuss things are often those who know that their own arguments aren’t any good.

  19. A number of lines of evidence do support the ROGD thesis.

    1. Teenage girls have been fad prone for a long time. In the past we have had bobby soxers, bulimia, anorexia nervosa, cutting, etc.
    2. The girls in question showed no signs of gender dysphoria growing up. A traditional trans identity starts very young.
    3. Bulimia may have peaked in the middle 1990s, with a significant fall since then.
    4. Diagnosis of anorexia nervosa peak at around age 16, with far smaller numbers for other age groups.
    5. There is strong evidence of a mental health crisis in teenage girls since 2010

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