For the 1968 Winter Games, the International Olympic Committee (IOC) introduced chromosomal testing to verify the sex of female athletes.* This replaced the invasive and degrading physical inspections that female athletes had been previously subject to [6]. But this seemingly straightforward test added a layer of complexity, that, instead of excluding men from women’s events, excluded women from women’s events, and perpetuated an already fraught history of policing women’s bodies.
Origins of sex testing in international sports
The road to the controversial practice of sex testing in sports was built on fear. First, we feared that athleticism posed a risk to femininity, resulting in the exclusion of women from sports altogether [18]. Eventually, we allowed women to engage in some "female-appropriate" activities but feared full inclusion [4]. As the events women could compete in expanded, they were still segregated from men's events on the basis that women were biologically inferior and needed to be protected [13].
As women's sports increased in popularity at an international level, Cold War tensions and a mid-twentieth-century obsession with winning led to fears that some countries were outright cheating by planting male imposters in women’s events [4,6,11,15]. Female athletes were required to provide medical certificates, but there was no broad oversight over those who issued them [8,11]. Eventually, nations were no longer trusted to judge the sex of their own female athletes and so, in 1966, formal, onsite sex testing was introduced to international sports [11,14].
At first, this relied on visual examination of genitals and secondary sex characteristics of female athletes [4,6,12,18]. After receiving backlash for this practice, the IAAF (“World Athletics” since 2019) trialled chromosomal tests as a replacement, which were deemed simpler, objective, and more dignified than direct physical and gynaecological examination [6].
But perhaps it was too simple. Reductive, even.
In 1967, Polish sprinter Ewa Klobukowska was the first athlete disqualified from international sports on the basis of chromosomal testing [6, 11, 15]. Klobukowska reportedly had “one chromosome too many”, and she was subsequently disqualified [6] despite meeting competitive and physiological standards of a female athlete: there was no suggestion that she exhibited male-pattern muscle mass or strength, and she also possessed typical female reproductive anatomy, giving birth the year following her disqualification.
In 1968, the IOC followed the IAAF's lead and formalised chromosomal testing for the Olympics.
The problem with chromosomal testing
Chromosomal sex testing presents shades of grey as black and white.
Sex chromosomes might seem like a straightforward indicator of sex –– XX for women, XY for men –– but they are only the first of many steps in the sex-determination process and their presence doesn’t guarantee the final anatomy of a person.
Women with Complete Androgen Insensitivity Syndrome (CAIS), for example, possess XY chromosomes but are insensitive to androgens (including testosterone) [discussed in more detail in Nature or Nurture: Insights from the Womb]. As a result, they develop as female [6,11,12,15,18], meaning there is no physiological sporting advantage associated with their chromosomal sex.
Additionally, XX and XY are not the only possible combinations, as seen in conditions like Turner syndrome (X), Klinfelter syndrome (XXY), and Jacobs syndrome (XYY). These variances highlight a more complex biological reality that challenges the binary understanding we have of sex.
We didn’t even know about sex chromosomes until the 20th century. The casual observer can't see them and they offer no insight into whether an athlete's biology provides an actual competitive advantage. Yet international sports-governing bodies were comfortable redefining sex based solely on these genetic structures, no combination of which guarantees whether a person develops as male or female.
Reducing sex to this single aspect of biology ignores the myriad of things that also affect sex development, including, but not limited to, exposure and sensitivity to testosterone. Testosterone level is where the focus eventually shifted to in international sports, but with its own pitfalls.
The problem with testosterone testing
In 2011, the IAAF replaced chromosomal testing with testosterone testing, conducted if suspicions about a female athlete's sex were raised based on her physique or performance. This required some female athletes to test below a threshold of testosterone to qualify for women’s events.
So, now you had to be “female enough”. Meanwhile, no upper testosterone limit existed for male athletes, even though a male with higher-than-average testosterone has the same presumed “unfair advantage” over male athletes as a female with higher-than-average testosterone would have over female athletes.
This hypocrisy reflects a deeper societal desire to regulate women's bodies, using science as a tool to limit women rather than explore, understand, and represent the full range of female potential.** Making testosterone a central qualifying factor maintains a very narrow definition of what it means to be female that reinforces the idea that women are inherently biologically inferior to men, even when there is proof to the contrary. Instead of recognising femininity as its own standard, including a wide range of abilities that can overlap with the abilities of men, femininity is defined in relation to masculinity, with no room for blurred lines.***
To keep women within this defined standard –– a comfortable distance below the male standard –– many female athletes face mandatory hormonal therapy or surgery to meet eligibility criteria [1], as well as damage to their public and self-perception, raising serious ethical concerns [20]. Between 2009 and 2010, South African runner, Caster Semenya, was required to take testosterone-reducing medication to compete in international sporting events. Reflecting on her experience, Semenya declared there was "no freaking way" she would do it again, adding that, she felt she had “been used”, being just 18 years old at the time [2].
It strikes me as both morally wrong and backwards thinking that we would rather coerce an athlete to medically alter her body without necessity or personal desire in order to meet our definition of “female” than question the accuracy of the definition itself.
In 2014, the IAAF's testosterone policy also affected Indian sprinter, Dutee Chand's inclusion in the Commonwealth Games. Chand appealed the decision and the Court of Arbitration for Sport (CAS) suspended the policy citing insufficient evidence that testosterone increases female athletic performance [1,4,9,17,19].
Even if it did, a woman who naturally produces more testosterone is still a woman –– a woman with hyperandrogenism. A woman should qualify for the women's category, just as a man with hyperandrogenism would qualify for the men’s category, even if he sits well beyond what is normal for other men.
It is also outright discriminatory to require female athletes to test below a defined range for a natural physical characteristic such as endogenous (naturally occurring) testosterone when male athletes don't.
The sexism of sex testing
The Olympics is a display of extremes. Taller, faster, and stronger athletes trained to the limits of human ability to perform far beyond what an average person could on very specific, intensive, physical tasks.
But only male athletes are allowed to push the limits to reach those extremes. There is no genetic, hormonal, or physiological advantage tested for and moderated in male athletes. In fact, their biological advantage is the entire point.
Meanwhile, when a female athlete crosses the limits associated with her sex, she is subject to scrutiny over her femininity, resulting in shaming, harassment, and accusations of being “too masculine”. We call for her to be tested and disqualified in an attempt to protect the fragility of the women's category as we've chosen to define it –– not based on what women can do, but what we think women should look like while doing it.
The recent controversy surrounding Algerian boxer, Imane Khelif, is a prime example of our fear-driven outrage at deviations from traditional femininity. Khelif faced massive online attack for her “masculine” appearance, with many outright accusing her of being a man after the purportedly corrupt International Boxing Association (IBA)**** claimed –– without evidence –– that she had failed sex tests [3]. Observers assumed that her “masculine” traits gave her an unfair advantage despite previously losing to other women before winning at the 2024 Olympics.
There is no intellectual consistency here, since, if Khelif had actually been a man, this track record would surely indicate that a male boxer doesn't necessarily have the advantage over female boxers based purely on sex. As much as we claim to be protecting women, it seems that there is also an element of protecting the male ego. How "embarrassing" it might be for a man to lose to a woman, even once. This might be why we allow mix-sex sports, such as pair figure skating and mixed doubles tennis, only insofar as male and female roles within them are supportive rather than competitive.
Keep in mind, not a single male imposter has been uncovered as a result of sex verification since it was introduced in the 1960s.◊ Instead, women are harassed and excluded for failing to conform to modern ideals of femininity.
Watching the Khelif controversy play out, it feels like we’ve come full circle, and are primarily judging female athletes, again, for not looking feminine enough. Meanwhile, the biological sex of strong, feminine women in pop-culture, such as Wonder Woman or Black Widow, would never be questioned. Why? Because their traditional Western feminine appearance appeals to the male gaze.
Real athletes’ bodies, though, aren’t the way they are to fit into whatever the modern beauty ideal is or to accentuate feminine features. They’re the way they are to excel at an event. For many of these events, the very traits that give a person the athletic edge are those associated with masculinity [11,18].◊◊
Female athletes with these traits –– taller, faster, stronger –– are still female, even if their appearance isn't in line with our subjective taste for traditional femininity.
Rethinking fairness in sports
Independent of sex, there are countless genetic, hormonal, and physiological variations that could lead to “unfair” advantages in sport [8,12,13,14,17]. Yet, we continue to focus on, test for, and regulate only advantages related to sex, with the focus firmly on controlling female deviation from the norm.
This is perhaps a natural progression of the historical discrimination of women in sports; sex segregation was only invented to exclude women from sport in the first place, and sex verification is just one part of this ongoing history, which uses science to:
Enforce a binary system on a non-binary population, ignoring what scientists actually tell us about sex and the flexibility of biological boundaries;
Reinforce sex segregation in sport based on the idea that women are biologically inferior to men despite considerable variation in male and female performance;
Pathologise and control women’s bodies in competitive sports in favour of traditional, Western ideals of femininity.
If we truly want to level the playing field and encourage fair competition, sex isn’t necessarily the most appropriate dividing line in all, or even most, cases, not least because we’re attempting to define boundaries that nature itself does not strictly define [9]. On a macro level, we recognise two sexes, but the macro is made up of individuals. Individuals make exceptions, and even within the binary, there is a spectrum. As a result, we simply lack the scientific ability to define biological sex with consistency [8].◊◊◊
It’s time to question our assumptions and ask ourselves: are they truly fair, inclusive, and reflective of what we now know about human biology? Could our definition of sex be expanded? Could we accept more overlap? Could we rely more on other physical attributes such as height and weight to foster fair competition? ◊◊◊◊
With more knowledge, understanding, and inclusivity in sports, perhaps we can create a world that better acknowledges and respects the complexity of being human.
----------
Footnotes
* Inaccurately called “gender verification”, since gender refers to a person’s identity, which may or may not align with their assigned biological sex (see also Footnote ◊◊◊). No genetic or hormonal test has the ability to determine a person’s gender because gender is a social construct. Gender also varies across culture and time. What we consider "female-appropriate" and "male-appropriate" changes depending on where and when you live.
** It also reflects a more general fear we have of the trans community, especially of trans women. As might be expected given the broader context of sexism in sports, trans women are disproportionately excluded from international competitive sports while trans men can compete in the men’s category without restriction.
*** Our discomfort with boundary pushing and blurred lines only in women's sporting categories reflects our subconscious tendency to see femaleness as a deviation from the male norm. This bias also explains why men's categories of sports (like football, golfing, cycling, and sprinting), are often considered the default, and more readily watched and taken seriously than women's categories of the same sports.
**** The Russian-led International Boxing Association (IBA) were stripped of their world governing status prior to the 2024 Olympics over integrity and governance issues; they did not provide information about what the tests consisted of [3].
◊ It is actually far more likely for women to plant themselves into men's events in order to be allowed to compete on equal footing [8].
◊◊ It’s worth noting that, having been created by men for men, more importance is placed on sports that showcase these more "masculine" traits in the first place. Sports that showcase physical abilities that tend to suit male bodies, such as strength, speed, and power, outnumber sports that showcase physical abilities that tend to suit female bodies, such as flexibility, agility, and balance [13]. In artistic gymnastics, men engage on activities that capitalise on strength rather than balance and smaller body size, such as the rings as opposed to the balance beam [7]. Men are also two to three times more likely to be mentioned in relation to sport than women, and when women in sports are mentioned, the focus is disproportionately on aesthetics [5].
◊◊◊ "Biological sex" doesn’t have a specific scientific meaning; there are no consistent, definitive biological criteria for categorising people as "biologically male" or "biologically female" [8]. Our biological classification of sex relies mostly on the observed external genitalia of a baby, which may or may not align with the expected reproductive function depending on a number of factors, including chromosomes, chemicals, and the presence of other biological structures.
◊◊◊◊ Some sports, like archery and shooting, have no evident reason to separate competitors by sex other than “it’s always been that way”. But other sports in which there is more of a gender split, like artistic gymnastics and figure skating, could also become more inclusive by allowing athletes to compete in events they choose based on individual talent rather than sex. This is how it used to be in gymnastics; men and women would train on the same things side-by-side, only to later be limited to specific activities based on sex in international sporting competitions [7]. In the interest of fair competition, we could introduce divisions based on relevant physical criteria other than sex, such as height and weight. Some historically more “masculine” sports, like wrestling and boxing, already do this, albeit it on top of sex segregation rather than instead of it. If we focussed more on physical criteria other than sex, some divisions might naturally include more women and others might naturally include more men, whilst also allowing for the variability and overlap we inevitably see in human biology.
----------
References
[1] BBC Sport (2015). Sport & Gender: A history of bad science and ‘biological racism’.
[2] BBC Sport (2019). Caster Semenya says testosterone case against IAAF has 'destroyed' her 'mentally and physically'.
[3] BBC Sport (2024). IOC says Khelif preparing legal action after new eligibility claims.
[4] Boyd, A. (2018). Back to the binary: How the Olympics struggle with separation of male and female. DePaul Journal of Sports Law, 14 (1), 1-32
[5] Cambridge Research (2016). Aesthetics over athletics when it comes to women in sport.
[6] Elsas, L. J., Ljungqvist, A., Ferguson-Smith, M. A., Simpson, J. L., Genel, M., Carlson, A. S., Ferris, E., de la Chapelle, A., Ehrhardt, A. A. (2000). Gender verification of female athletes. Genetics in Medicine, 2 (4), 249-254
[7] Federation Internationale de Gymnastique (2020). Why are there four events for women and six for men?
[8] Feigenbaum, J. (2019). Shades of gray: Sex, gender, and fairness in sport. Barbell Medicine.
[9] Garcés de Marcilla-Musté (2022). You ain’t woman enough: Tracing the policing of intersexuality in sports and the clinic. Social & Legal Studies, 1-24
[10] Ha, N. Q., Dworkin, S. L., Martínez-Patiño, M. J., Rogol, A. D., Rosario, V., Sánchez, F. J., Wrynn, A., & Vilain, E. (2014). Handling over sex? Sport, science, and equity. Archives of Sexual Behavior, 43, 1035-1042
[11] Heggie, V. (2010). Testing sex and gender in sports; reinventing, reimagining, and reconstructing histories. Endeavour, 34 (4), 157-163
[12] Karkazis, K, Jordan-Young, R, Davis, G., and Camporesi, S. (2012). Out of bounds? A critique of the new policies on hyperandrogenism in elite female athletes. The American Journal of Bioethics, 12 (7), 3-16
[13] Leong, N. (2018). Against women's sports. Washington University Law Review, 95 (5), 1251-1292
[14] Padawer, R. (2016). The humiliating practice of sex-testing female athletes. New York Times Magazine
[14] Ritche, R., Reynard, J., & Lewis, T. Intersex and the Olympic Games. Journal of the Royal Society of Medicine, 101 (8), 395-399
[16] Roberson D., Pak, H., & Hanley, J. R. (2008). Categorical perception of colour in left and right visual field is verbally mediated: evidence from Korean. Cognition 107 (2), 752-762
[17] Rogol, A. D., & Pieper, L. P. (2017). Genes, gender, hormones, and doping in sport: A convoluted tale. Frontiers in Endocrinology, 12 (8), 251
[18] Schweinbenz, A. N., & Cronk, A. (2010). Femininity control at the Olympic Games. Thirdspace: A Journal of Feminist Theory and Culture, 9 (2)
[19] Sudai, M. (2017). The testosterone rule – constructing fairness in professional sport. Journal of Law and the Biosciences, 4 (1), 181-193
[20] Weisemann, C. (2011) Is there a right not to know one's sex? The ethics of 'gender verification' in women's sports competitions. Journal of Medical Ethics, 37 (4), 216-220
Comentarios