What No One Is Telling You About Caster Semenya: She Has XY Chromosomes

Plus The Usain Bolt/Michael Phelps Comparisons Don’t Work and More

By Robert Johnson
May 2, 2019

Let me start by saying, none of what I write below should be viewed as a personal attack on Caster Semenya. I have the utmost respect for her. Instead of writing up tons of praise for her, I’ll just share a tweet that one of my employees sent out yesterday as it’s better than anything I could have written myself.

That being said, I’m writing this column as I feel like the average person who hasn’t been following the Caster Semenya situation closely and woke up yesterday to see Semenya headlines in newspapers and on websites across the globe likely has no idea what is going on. The mainstream reporting on Semenya is very misleading, to say the least so let me share a few key facts that you likely haven’t read anywhere else.

Semenya flexing her muscles at the Pre Classic in 2018

1) Caster Semenya Has XY Chromosomes

It’s absolutely mind-boggling that virtually every major outlet in the world reporting the Court of Arbitration for Sport ruling yesterday has failed to mention one of the most important facts of the entire case. Caster Semenya has XY chromosomes. It was generally accepted by people following the case closely that Semenya was XY, but now it’s been confirmed as fact since the CAS press release specifically says, “The DSD covered by the Regulations are limited to athletes with ’46 XY DSD’ – i.e. conditions where the affected individual has XY chromosomes.” If she wasn’t XY, the IAAF’s regulations wouldn’t apply to her and she’d have no reason to challenge them.

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(In case you forgot what you learned in junior high biology, typically females have XX chromosomes while males are XY).

How the Associated Press, ReutersNY Times, NPR, Washington Post, and BBC could all leave this CRUCIAL fact out of their reporting is beyond me. Not a single one of them mentioned it at all. It should have been in the lead paragraph of every story so people like my mother, who sent me a confused email after she saw an article on Semenya, can really understand what this is all about. Instead, the closest we get to the truth was that some of the articles talked about how Semenya has intersex “traits” or “characteristics.” Let’s be real, if you are an XY woman, you are the very definition of what virtually everyone would think of as intersex.

Because of the glaring XY omission, many across the globe ended up reading opening paragraphs like this from the front page of the New York Times:

Female track athletes with naturally elevated levels of testosterone must decrease the hormone to participate in certain races at major competitions like the Olympics, the highest court in international sports said Wednesday in a landmark ruling amid the pitched debate over who can compete in women’s events.

If I had been writing for the NY Times, I’d have added just six words and there would have been no confusion as to what really happened.

Intersex track athletes with XY chromosomes and naturally elevated levels of testosterone must decrease the hormone to participate in certain races versus women at major competitions like the Olympics, the highest court in international sports said Wednesday in a landmark ruling amid the pitched debate over who can compete in women’s events.

The NY Times put Semenya on its front page but somehow failed to mention Semenya is XY.

This is an incredibly complex issue, and one of the reasons for that complexity is that the IAAF has two categories in which athletes can compete: male and female. The problem is, human biology doesn’t always neatly divide into male or female. Some people — intersex people — have traits of both sexes. Semenya isn’t male, but in addition to Y chromosomes, she is believed to have internal testes and lack a womb or ovaries — characteristics we don’t traditionally associate with females. However, you’d likely never know that from reading the coverage in the mainstream press on Wednesday.

The issue is complex but nuance matters. Our own title on the homepage of LetsRun.com about the news was originally incorrect. Originally our headline on the homepage said, “Caster Semenya Loses CAS Case, Can Only Compete In 800 If She Suppresses Testosterone.” A visitor pointed out that title was inaccurate as Semenya was free to compete in the “open” or “men’s” category without suppressing her testosterone. So we changed it  to “Caster Semenya Loses CAS Case, Can Only Compete In Women’s 800 If She Suppresses Testosterone.”

2) The “Michael Phelps” or “Usain Bolt” Genetic Outliers Argument Isn’t A Good One

Many people who support Semenya use the argument that elite sports are often about genetic outliers dominating. Usain Bolt had really long legs and Michael Phelps had really long arms, so why can’t Semenya have really high testosterone?

That’s a bad analogy. Sports organizations don’t classify athletes by arm or leg length, but they do classify athletes by sex. If they didn’t, women wouldn’t have a chance to excel at the very top levels of sport as men’s world record are consistently 10-12% better than women’s world records in sports like track and swimming. In tennis, even a great like Serena Williams admits she couldn’t get a game off a top male pro like Andy Murray. If sports organizations didn’t classify by sex, there would be almost zero female Olympians save for sports like maybe equestrian.

There is no human right to compete in a particular category of professional sports. Sports governing bodies exclude certain types of people from certain categories of sports all the time. In boxing, a 210-pound boxer can’t fight as a flyweight (112 lb max) as the flyweight would have little realistic chance of winning.

To say that an XY human can’t compete in the women’s category of professional sports unless they lower their testosterone below 5 nmol/L — a figure that is still 7.5 times the value of the average woman competing at the 2011 and 2013 track and field World Championships and a figure that not a single healthy woman born with XX chromosomes, ovaries, and producing estrogen at puberty can reach — isn’t a huge human rights travesty. It’s a protection of women’s sports.

3) No, Intersex People Don’t Make Up Anywhere Close To 1.7% Of The Population (Being Intersex Isn’t Nearly As Common As Having Red Hair), But All Three Women’s Olympic 800 Medallists From 2016 Are Believed To Be Intersex


Again, this is totally misleading and biased reporting.

Embed from Getty Images

Semenya (l) in HS.

The 1.7% figure comes from a book written by biologist Anne Fausto-Sterling in 2000 called Sexing the Body: Gender Politics and the Construction of Sexuality. But Fausto-Sterling used a very broad definition of the word “intersex” — one much broader than she herself used in the past. As Dr. Leonard Sax has pointed out both on his website and in a scientific paper, if you limit the term intersex to its traditional meaning — to refer either to individuals who have XY chromosomes with predominantly female anatomy, XX chromosomes with predominantly male anatomy, or ambiguous or mixed genitalia (which is what Fausto-Sterling herself did in her 1993 essay “The Five Sexes”), then the rate of intersex births is just .018% — less than two out of every 10,000 people.

The crazy thing about the Semenya case is that even though intersex births like Semenya’s are extremely rare it’s believed that all three of the medallists in the 2016 Olympic women’s 800 – Caster Semenya, Francine Niyonsaba and Margaret Wambui — are intersex. Yes, all three. If that doesn’t make you understand from a simple odds perspective that there needs to be a limit on testosterone in women’s sports, then I don’t know what will. Of course, common sense also tells us that most human beings that have XY chromosomes gain a huge advantage in sports once they hit puberty, mainly due to increased testosterone levels.

How big of an advantage is it? Well sports scientist Ross Tucker – who actually testified on behalf of Semenya before the Court of Arbitration for Sport as he thought one of the IAAF’s studies used against Semenya was flawed but also supports, in theory, limits on testosterone for women in sports – has described the presence of the Y-chromosome as the “THE single greatest genetic “advantage” a person can have.”

I’ll conclude this column with an excerpt from what Tucker wrote on the LetRun.com forum in 2016:

That premise hopefully agreed, we then see that the presence of the Y-chromosome is THE single greatest genetic “advantage” a person can have. That doesn’t mean that all men outperform all women, but it means that for elite sport discussion, that Y-chromosome, and specifically the SRY gene on it, which directs the formation of testes and the production of Testosterone, is a key criteria on which to separate people into categories.

So going back to the premise that women’s sport is the PROTECTED category, and that this protection must exist because of the insurmountable and powerful effects of testosterone, my opinion on this is that it is fair and correct to set an upper limit for that testosterone…

The advantage enjoyed by a Semenya is not the same as the one enjoyed by say, Usain Bolt, or LeBron James, or Michael Phelps, because we don’t compete in categories of fast-twitch fiber, or height, or foot size (pick your over simplification for performance here). So Semenya has a genetic advantage, by virtue of A) having a Y-chromosome and testes, and B) being unable to use that T and/or one of its derivatives enough to have developed fully male.

More: Talk about the Semenya ruling on our world famous messageboard/ fan forum:

From the LRC Archives:

November 8, 2022: Gender identity has no place in sport
April 22, 2018:
LRC Guest Column From 1968 Boston Marathon Winner Amby Burfoot:  The Whole World Is Watching: Caster Semenya vs IAAF
September 19, 2014: LRC Guest Column from Joanna Harper: A Brief History of Intersex Athletes in Sport
2009: The LetsRun.com Youtube video interview of Semenya that has nearly a million page views as it was one of the first video interviews of Semenya (an excerpt of it appeared on Good Morning America):

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