Blurred Lines: Trans and Intersex Inclusion in Women's Sports

Why we can’t treat trans women the same as we currently do women athletes with disorders of sex development

Why care about women’s sports at all? 

Sports took up a pretty large chunk of my free time as a kid and young teen. In addition to being a competitive highland dancer, I participated in cross country and middle distance track events from middle school until my mid-teens. In high school our running coach even convinced me to join the wrestling team for two years. I only ever won one fight, when I finally faced a taller and lankier opponent (my body type at the time was not ideal for the sport), but I had a lot of fun. 

Our coach was unusually supportive of the girls’ teams both in running and wrestling, perhaps putting even more focus on our performance than he did on the boys. He didn’t treat us with kid gloves, made us spar with the boys and expected 5 days a week adherence at practice plus weekend conditioning. It wasn’t that our coach was a big feminist, it was just that he cared about winning school titles and correctly recognized that there was more low hanging fruit to be plucked by encouraging the girls in particular. This was especially true for wrestling where our coach’s recruitment of girls paid off. We had around eight girls on the wrestling team vs. the two or three most other schools had, which made winning tournaments a breeze.

Overall, I’m glad that I spent so much time on sports growing up. It gave me a basis of fitness that made it much easier to rebound from sedentary periods in my 20s, built some discipline and forced me to practice pushing through performance anxiety. And even though I sucked, knowing the basics of how to take someone down is a cool skill. I think it’s important that other young women have the opportunities to get these experiences as well. Participation in sports can build confidence, improve your sense of physical embodiment and provide an outlet for healthy expressions of competitive aggression. Of course, that doesn’t imply that I think it’s important for women to be equally represented or compensated in pro sports leagues.

Prior to the passing of Title IX in 1972, which provides that “No person in the United States shall, on the basis of sex, be excluded from participation in, be denied the benefits of, or be subjected to discrimination under any education program or activity receiving Federal financial assistance”, many girls didn’t have the same opportunities to participate in school based sports programs as the boys did. I’m not going to discuss the ways in which Title IX has been extended well beyond giving girls the opportunity to participate in athletics to requiring schools to force complete parity in participation, despite the quite obvious fact that women are on average less interested in sports relative to boys, but

Richard Hanania

covers it well in The Origins of Woke. 

Regardless, at the time, the degree to which performance differences resulted from socialization and lack of opportunity vs. biological differences wasn’t entirely clear. In the years immediately after the passage of Title IX a general improvement in the performance of elite female athletes relative to males was observed, but, as Carole Hooven notes in her book Testosterone, this didn’t last all that long: 

From 1972 to 1980, the sex differences in Olympic trial times went from 17 percent to 13 percent (running) and from 13 percent to 11 percent (swimming). In the last forty years, the gap hasn’t budged.

At the elite level, there is generally no overlap between the female and male participants since, in almost all cases, the worst elite male athlete is better than the best elite female athlete. Even Serena, by far the best female tennis player of all time, says that, from her perspective, “men’s tennis and women’s tennis are completely almost two separate sports” and that “I only want to play girls because I don’t want to be embarrassed”. 

And even for the general population, sex segregation makes sports much more fun for girls and women. I briefly played on a mixed-gender recreational soccer team during my master’s degree and after that experience I vowed I’d never again play with the boys. It just isn’t fun. This persistent gap between male and female athletes is precisely why we need sex segregation if girls and women are to meaningfully participate in sports. But controversy around sex segregation goes back much further than the discussion regarding how to deal with trans women athletes.

Unfortunately, sex segregation is one sided and can seem creepy

Because weight classes are used in many combat sports, weigh-ins matter a lot for competition. Everyone recognizes that without weigh-ins people would fudge the numbers to fight in the weight class below their own because it would be an obvious advantage. This is why you normally end up with everyone in a weight class weighing in right near the top of the range - if the lower weight class was in sight they’d lose the extra pounds to qualify for it. And in addition, most fighters' day to day weight will be higher than their fighting weight. Even high school level wrestlers would do things like forgo water the day ahead of weigh-ins in order to make the cut.

The reason for this, of course, is that weight classes exist to organize combatants based on size so that real skill, rather than brute strength, will determine who wins. This segmenting also allows a wider variety of people to have the opportunity to compete in and win major competitions. Sex segregation is done for a similar reason - to allow women to compete at an elite level against one another. When the issue of whether it’s “fair” to include trans women in women’s sports comes up, some people respond that elite sports isn’t about fairness at all, but about seeing human excellence on display. But if we really only want to watch the most excellent of the excellent, we’d only have one category and we’d only be watching men.

At low levels, no one is asked to do a “sex verification” in order to compete in the women’s category. In part, this is because it’s much harder to fake being a woman since it’s part of how you’re identified by others, it’s on your identification documents etc. than it is to lie about your weight. But at the Olympic level, various forms of testing have been required on and off over the past century.

Many highlight the “naked parade” used to confirm female sex by the I.A.A.F. (now World Athletics) in 1966 as a particularly low point in the sex testing of women athletes. And it’s easy to see why many view these sorts of tests in general as invasive, sexist and humiliating. After all, these tests can include genital exams and male athletes are never subjected to this indignity. But of course, there’s an obvious reason to test women and not men. Because the men basically compete in the “open” category. It’s already the hardest category and there’s no advantage to be gained by pretending you belong in it. It’s not surprising that we aren’t discussing the inclusion of trans men in male sports (which typically only requires self-ID), because none of them would make it into the male elite level if they tried. 

Truly intersex individuals are extremely rare, but they are overrepresented among elite athletes competing in the women’s category. This is because there are particular disorders of sex development (DSDs) which provide a clear performance advantage over female athletes. World Athletics, which ratifies all world records for track and field and is recognized by the Olympic committee gives us a sense of the scale of the apparent advantage in an FAQ about their intersex regulations:

We have seen in a decade and more of research that approximately 7.1 in every 1000 elite female athletes in our sport are DSD athletes with very high testosterone levels in the male range.  [...] This frequency of DSD individuals in the elite athlete population is around 140 times higher than you will find in the general female population, and their presence on the podium is much more frequent even than this. The CAS accepted that this demonstrates, in statistical terms, that they have a significant performance advantage.

Caster Semenya, a middle-distance track runner, is probably the best known example of an athlete whose sex has been questioned and who many suspect was the proximate motivation for the current regulations on athletes with disorders of sex development (DSDs). Semenya has a rare disorder called 5-alpha reductase deficiency (5-ARD) which prevents the typical development of male genitalia in utero in an individual with XY chromosomes. These individuals typically have internal testicles (which pump out testosterone at male-typical levels) rather than a uterus, but female typical or ambiguous genitalia and, as in Semenya’s case, are often identified as female at birth. How does this work you ask?

A primer on relevant DSDs (5-ARD and CAIS/PAIS) from Carole Hooven

Carole Hooven explains the “bipotential” gonad in her chapter, Making Boys:

During early fetal development in both sexes, groups of undifferentiated cells cluster together on the ridges of structures that will later become our kidneys. These “primordial” or “bipotential” gonads are identical in male and female fetuses up until week six, when their cells will begin to differentiate and gather together to create one or the other type of gonad. The path those cells take depends on whether genes in the DNA inside of the cells hear a loud request, in the form of high levels of a protein called SRY, which [...] is coded for by a gene [...] located [...] on the Y chromosome. [...] In this way, the SRY gene leads to the production of specific proteins inside the cells of the primordial gonad. These proteins cause the cells to take on the special characteristics of testicular cells (and also to repress genes that lead to ovarian cells). Ultimately, the Y chromosome and the expression of SRY, along with many other “downstream” genes, cause the cluster of cells that comprises the primordial gonad to form testes rather than ovaries.

Basically, the SRY gene, which is located on the Y chromosome, provides the instruction to develop testicles and to suppress the development of ovaries. Irrelevant for present purposes but Carole additionally notes that “Ovaries can also be produced in an XY individual if SOX9 or other important genes in the “make a testis” pathway don’t work as usual. In these cases, the fetus will typically develop as a female, albeit with ovaries that may not be fully functional in adulthood.” As for the development of external genitalia, without the presence of either particular androgens or properly functioning androgen receptors, the fetus will develop female typical or ambiguous genitalia. From Carole again:

Not only do we start out with bipotential gonads that can develop into either ovaries or testes, our early internal reproductive anatomy is also gender-convertible. Early on in fetal life we all develop two sets of primordial duct systems, but after about eight weeks, one of them degenerates while the other continues to develop. [...] The female duct system is the default: it will develop without any specific hormonal stimulation, unlike the male duct system. [... In addition] our external genitalia [...] arise from the very same embryonic structures. The penis is basically a huge clitoris and the line that runs down the underside of the penis are basically fused labia.

But some XY individuals have complete or partial androgen insensitivity syndrome (CAIS/PAIS). In cases like these, even though the individual has high levels of T, they won’t develop male typical genitalia because, as Carole says, “Hormones like testosterone fit into their receptors rather like keys into locks, and “open the door” to all sorts of changes. If the lock is broken the key is useless.” And, as with the duct system, female typical external genitalia is more or less the default. But for individuals like Semenya, their androgen receptors work just fine. Her atypical development, as the name of her disorder suggests, is related to a particular androgen deficiency. As Carole explains in her chapter, T on the Brain: 

The fetus will not develop a penis and scrotum unless the androgen receptors in the precursor tissues—the undifferentiated, early reproductive tissues—receive extra stimulation, more than testosterone alone can provide. This extra stimulation comes from the more potent androgen dihydrotestosterone (DHT), which is produced from testosterone, with the help of the enzyme 5-alpha reductase

Hence why individuals with 5-alpha reductase deficiency, like Semenya, generally won’t develop male typical external genitalia in utero and can be identified as female at birth, just like individuals with CAIS. Come puberty, both CAIS and 5-ARD individuals will not get their period since they don’t have ovaries, and in some cases this is when they find out about their DSD.

There’s a significant difference between individuals with 5-ARD vs. those with CAIS however, which is that individuals with 5-ARD are still sensitive to testosterone. And so individuals with 5-ARD experience much of the masculinizing effects of male puberty while those with CAIS do not. Both types of individuals have testes which are producing male levels of testosterone, but since those with CAIS are insensitive to its effects it doesn’t lead to the increased musculature, increased bone strength etc. which is typical of male puberty.

Track and field regulations for athletes with DSDs and for trans women 

Currently, the World Athletics eligibility regulations require athletes to inform and provide medical history should they have a DSD. If an athlete competing in the women’s category is suspected of having a relevant DSD, a case can be opened and the athlete can be submitted to sex testing. The regulations allow intersex individuals, including those with 5-ARD like Semenya, to participate in international women’s competitions, but require them to lower their testosterone to within the female range for a period of 24 months before competition. This is true for all XY individuals with DSDs causing high levels of testosterone, unless they can show that they have a condition like CAIS for which this does not lead to a performance advantage.

As for trans women, the current regulations exclude trans athletes that have gone through male puberty:

To be eligible to compete in the female classification at a World Rankings Competition and to have recognised any World Record performance in the female classification at a competition that is not a World Rankings Competition, a Transgender female Athlete must [...] not have experienced any part of male puberty either beyond Tanner Stage 2 or after age 12 (whichever comes first). [...] Since puberty they must have continuously maintained the concentration of testosterone in their serum below 2.5 nmol/L. [... And] They must continue to maintain the concentration of testosterone in their serum below 2.5 nmol/L at all times (i.e., whether they are in competition or out of competition) for so long as they wish to retain eligibility to compete in the female classification at World Rankings Competitions and/or have recognised any World Record performance in the female classification at a competition that is not a World Rankings Competition.

While this is sensible from the perspective of preventing trans women who’ve had the performance enhancing benefits that come from male puberty from competing with women, it has some potential issues. For one thing, the requirement that intervention must occur by age 12 could create a new incentive for young, athletic boys with gender dysphoria to use puberty blockers and cross sex hormones very early.

It also means that trans women athletes may or may not be eligible simply as a result of the youth gender medicine norms in their country of origin. For instance, with the publication of the Cass report, puberty blockers are available only under a research protocol and masculinizing/feminizing hormones will be available at 16. So, a future trans woman who grew up in the UK will not have access to the types of treatments which would be required for her to compete in women’s sports in the future.

These regulations, again, sensible in terms of keeping things fair for female athletes, are also potentially inconsistent with the regulations on athletes with 5-ARD, like Semenya. As discussed above, these individuals apparently receive many of the performance enhancing benefits associated with male puberty. Recall that World Athletics data indicates that the frequency of individuals with DSDs, while still very rare among elite women’s athletes, “is around 140 times higher than you will find in the general female population, and their presence on the podium is much more frequent even than this.” And, it’s also likely relevant to know that it’s not at all uncommon for individuals with 5-ARD who were identified as female from birth to transition to a male gender identity at or shortly after puberty. 

Carole Hooven highlights the case of the “guevedoces” which literally translates to “penis at 12”, a group of people with 5-ARD discovered to exist at an extremely high rate within two villages in the Dominican Republic in the early 1970s. For many of these individuals, puberty brought on physical and cognitive changes more consistent with a male gender identity including penis growth and sometimes the descending of testicles. As Hooven notes, despite the fact that 5-ARD prevents the masculinization of the genitals in utero, “high levels of DHT aren’t absolutely necessary to masculinize the genitals in puberty. High levels of T can do a decent job on their own”. Imperator-McGinley notes in her paper on gender identity among this population that “Eighteen of 38 affected subjects were unambiguously raised as girls, yet during or after puberty, 17 of 18 changed to a male-gender identity and 16 of 18 to a male-gender role.”

These individuals typically have male levels of bone mineral density (this link says these patients have “normal” bone density, but is referring to them as males) and male patterns of musculature coming out of puberty, yet they’re allowed to compete so long as they’ve been reducing their testosterone to within the female range for at least 24 months. And while reducing their testosterone almost surely reduces their performance advantage, it seems likely that they would have similar advantages to a trans woman who went through male puberty and has since been doing cross-sex hormone therapy for an equivalent number of years. 

Should we treat AFAB intersex individuals differently from trans women?

If all we care about is the degree of physical advantage, then from my reading of the situation, athletes like Semenya should be regulated in a nearly identical way to trans women athletes. However, there’s more to think about here. 

First, people with 5-ARD and other relevant DSDs are far more rare than trans women are. It’s hard to find a precise estimate of how frequent 5-ARD, female-identified adults are in the general population, but the World Athletics quote I included on overrepresentation implies that the frequency of DSDs in general is something like 1 in 20,000. This source appears to put the frequency at a slightly higher level, given that it estimates that congenital adrenal hyperplasia (CAH), a disorder where XX individuals produce high levels of androgens beginning in utero (which among other effects can lead to ambiguous genitalia), occurs among approximately 1 in 15,000 girls. 

I’ve probably referenced CAH girls in previous pieces as they’ve been important in demonstrating how hormones alone can cause sex differences, such as more male-typical play patterns, even in the absence of male socialization. CAH girls are also likely overrepresented among elite female athletes, and produce higher than typical levels of androgens if untreated, but because they have XX chromosomes the World Athletics regulations don’t apply to them, which some have complained is inconsistent and unfair to athletes like Semenya.

Regardless, we can assume that the frequency of relevant DSDs is on the order of 1 in 10,000 whereas male to female trans individuals are far more common, with estimates on the order of 40-60 in 10,000. The frequency of trans individuals is also likely to rise over time as we’ve seen an increase in young people identifying as trans. If we assume that the advantages trans women who went through male puberty would have are largely similar to those seen in individuals with 5-ARD, we’d expect them to end up something like the 140x overrepresented among elite women athletes. Plus, World Athletics notes that athletes with DSDs are even more overrepresented on the podium. 

As things stand, this would imply that over time it would not be surprising if trans women came to comprise a majority of elite women athletes should they be allowed to compete after having gone through male puberty and under similar regulations to those that apply to individuals with 5-ARD. Elite female athletes already complain about the inclusion of individuals like Semenya - if females became a minority at the elite level, or even if they only became a minority on the podium, I’d expect that tolerating these sorts of differences would most likely become untenable.

In addition to the frequency issue, I think many intuit that it’s somehow less fair to exclude women like Semenya, who were identified as female from birth and raised as girls, than it is to exclude trans women. Many of the women with XY chromosomes and DSDs don’t even find out about their condition until puberty. Plus, it’s possible that there are additional male-specific performance benefits which, because they don’t produce sufficient levels of DHT, are not fully developed among this population. Your personal view on this might depend on the degree to which you think being trans is a “choice” vs. something that an individual is “born with”.

Representation matters?

I’m not entirely sure how to conclude. It took me ~3,500 words just to explore the issue with respect to track and field athletes and it’s possible that the relevant performance characteristics will differ by sport as will the appropriate regulations. I don’t really know what exactly we should do about this issue. But although it affects a vanishingly small percentage of the population directly, elite athletes, I find it fascinating.

While elite athletes are a tiny population, the population of girls and boys who look up to them is much more significant. And while women’s sports will likely never draw the sort of attention and importance that men’s sports do, it seems like a good thing that athletic young girls can aspire to be like the women they see on the podium. But if none of those women are female… I’m not quite sure they’ll be able to see themselves in those role models in the same way.