I focused on those athletes because they’re the motivating factors behind this decision. DSD males and trans women both have the innate advantage of male puberty, which is why the IOC is making this move. To focus specifically on trans women, here’s one example out of many on why we have separate competitions for men and women (not a sympathetic article, but factual):

https://quillette.com/2025/10/30/the-scandal-of-ana-caldas-and-the-case-for-sex-screening-in-female-athletics/

In 2016, a Portuguese-American athlete named Hannah Caldas participated in the female category of the “Monstar Games,” a large fitness competition held in Rio de Janeiro. The Games included a weightlifting challenge run by Brazil’s Fortify Equipamentos sporting-goods retail chain, whereby contestants were scored on how many times they could lift heavy balls over their heads in the space of a minute.

An event official asked Caldas to choose between one of two balls—weighing thirty and seventy pounds, respectively.

“How about the 120?” Caldas replied, pointing to a third, much larger ball.

According to Caldas’s subsequent recollection, the official explained that this wasn’t a realistic option for contestants registered in the female category, since “no girls had been able to pick it up.”

“Challenge accepted!” Caldas later wrote on Instagram. While a fellow athlete named Joyce Rodrigues filmed, Caldas proceeded to heave the 120-pound weight into the air no fewer than sixteen times.

The idea that biological males don’t have an athletic advantage over females is plainly, obviously wrong

USMS records indicate that it was 23 January 2009 when a new swimming sensation identified as “Hannah Caldas” suddenly appeared on the women’s USMS racing scene. Despite being a complete unknown, Caldas immediately began dominating the competition in the 30–34-year-old age group—including winning five out of six events at Caldas’s inaugural tournament in Charlotte, NC. The performances were so astounding that Caldas reportedly almost hit a benchmark time for Portugal’s women’s Olympic swimming team (missing the cut by a mere 0.3 seconds).

This would be a shockingly impressive athletic run for anyone—let alone a (nominal) rookie such as Caldas, who was able to blast past former NCAA swimming stars with ease despite having no collegiate training as a female athlete; and who was, by this point in life, a full decade past the prime age for Olympic-calibre swimmers.

That’s why the argument that trans women are only 0.X% of competitors doesn’t hold any water. They can still dominate a sport and deny medals to any cis women competing. This is now becoming an issue at the Olympic level which is why the IOC is addressing it, but people have tracked many more cases at sites like https://hecheated.org/. Whether or not you like the people behind that or similar sites, it’s more about the facts.

Let me know where you’re misunderstanding it and I’ll do my best to help break it down!

Sex is binary because there are two sizes of gametes, large and small. Those two are the only options, and thus sex is a binary. In humans, sex is determined by chromosomes, but defined by gamete size. Variations in phenotype and genotype are variations within a sex.

You might be confused by the term “hermaphrodite”. It’s possible for some organisms to produce both gamete sizes! But sex is still a binary, because you’ll notice they produce both sizes. Some animals can even change sex during their lifetimes or have their sex determined by temperature while they develop 🤯 It’s true! But humans aren’t like that, we’re sexually dimorphic. Our bodies are organized around producing one or the other of two gamete sizes for our entire lives.

Now you might be wondering why we care about defining sex. Why bother? 🤔 The answer is because it’s the only defining trait that works across an enormous swath of the animal kingdom! Biology is hard and messy and it’s amazing we found such a handy distinction. Some organisms such as fungi have mating types instead of sex, but in anisogamous species we define sex by gamete size because it’s the only coherent definition.

I’ll help you out with the first sentence!

Sex is the biological trait that determines whether a sexually reproducing organism produces male or female gametes.

Glad I can help you learn something today! Sex is defined by gamete size. Unfortunately, disputing like you’ve done is unscientific. The linked article that goes over the definition is a great place to start for a beginner though!

I linked to it because it’s a sympathetic source that you would actually read. I realized that it was mealy-mouthed about gender vs sex when I linked it, but had hoped that you could see that even a sympathetic take acknowledges that Khelif is male.

Intersex is a confusing term, and it has confused you. That’s OK though! Sex is still not a spectrum. Khelif is male due to producing the smaller of two (i.e. binary) gamete sizes in humans, which is how sex is defined. 5αR2D is a male DSD, which means Khelif is ineligible for women’s sports. That’s what men’s and open leagues are for though!

I guess this is on me, for assuming you’d comprehend the article. I’ll explain it to you though!

Sex is not a spectrum. Sex is a binary defined by the size of gametes your body is organized around producing. Sex phenotypes and genotypes are a spectrum, and Snopes is hoping that you’re too ignorant to understand that, which regrettably you are. Which is OK! Everyone’s ignorant of lots of stuff, this is a great time to learn something. When Snopes says things like “In other words, there are several ways to define gender”, you can completely ignore that, because it’s irrelevant to participation in women’s sports. There is no evidence that Khelif is female, and this entire matter could be put to rest with a simple, non-invasive, cheap cheek swab that would prove to everyone that Khelif is in fact female. It is good that the IOC will implement sex testing and put this matter to rest so we can focus on more important things.

Gender is a spectrum though! It’s a reflection of how you live in your body and that’s great! Except in sports, it makes a difference if you’ve gone through male puberty. Khelif has gone through male puberty on account of being male, which is unfair to female competitors. Trans people should get to compete in sports! But trans women that have gone through male puberty and males with DSDs (aka intersex, which is a confusing term for this reason) should compete in open/men’s leagues because of innate biological advantage. The IOC is doing this because they followed the scientific evidence.

Why would I delete my comment? I’m well aware of what the link says. Khelif is biologically male and even in the sympathetic article I linked they don’t dispute that.

Gender isn’t binary, but sex is. Snopes is trying to confuse you by conflating sex and gender, but nobody’s arguing about what gender Khelif is.

It’s easy to dismiss that as a “random-ass blog” because you’re engaging in motivated reasoning, but it’s certainly not the only evidence:

https://www.snopes.com/news/2024/11/20/imane-khelif-medical-records/

Again, you have nothing. It’s fun to argue and all, but I’ll remind anyone reading this that until evidence of Khelif being female is presented, any other response is sophistry meant to distract you.

Fun meme. But where is your proof otherwise?

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Imane Khelif, Lin Yu Ting, and Caster Semenya are all biologically male (not trans, DSD males incorrectly assigned female at birth). No cis women won a medal in the 2016 Rio 800m, all of the medal winners were DSD male. That would likely continue to be the case except they are no longer eligible for the women’s category.

Michael Phelps’ records have already been surpassed. DSD males competing in women’s sports set records that cis woman will never surpass. It is not surprising that the vast majority of people find this unfair. The IOC is doing the right thing.

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