A controversial genetic test will return to the LA Olympics. It also happened in '84

The International Olympic Committee issued a new policy last month, banning transgender women from participating in women's sports starting at the 2028 Summer Games and requiring all athletes who want to compete in the female category to undergo genetic testing.

The policy represents a significant inflection point in the ongoing political battle over trans women's participation in sports at all levels, including in California. It also marks a return to genetic tests that for decades dictated women's participation in the Olympics, and excluded transgender and many intersex athletes — those whose sex characteristics don't fall into the binary categories of male or female.

Genetic testing was required of women athletes for much of the second half of the 20th century, including the last time Los Angeles hosted the Olympic Games in 1984. Athletes had to present "certificates of femininity," according to the official report on the 1984 Games.

Those types of tests were stopped after the 1996 Games in Atlanta amid questions about their scientific efficacy and ability to assess what was an "unfair advantage," according to the IOC's own retelling.

Blanket genetic testing will return to the L.A. Olympics in 2028, bringing with it questions about how it will be implemented and who it will keep off the Olympic stage.

IOC says the science is settled. Some experts disagree

How to measure fairness in women's competition has been debated for at least a century, and different approaches have been used and abandoned over the decades. In recent years, the IOC had stopped requiring genetic tests and left rules around sex testing to individual athletic federations.

When IOC President Kirsty Coventry announced that the IOC would re-introduce a mandatory genetic test for all female Olympic athletes last month, she presented it as the final word on who can and can't participate in women's sports.

IOC President Kirsty Coventry speaks during an IOC Executive Board press conference on Feb. 01, 2026 in Milan, Italy.

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All women Olympic athletes will have to take a test to identify if they have an SRY gene, which is on the Y chromosome. According to the IOC news release, that SRY gene represents "highly accurate evidence that an athlete has experienced male sex development." Those with the gene will be excluded from competition except in some limited cases where the athlete is found to not to "benefit from the anabolic and/or performance-enhancing effects of testosterone."

"At the Olympic Games, even the smallest margins can be the difference between victory and defeat," Coventry said. "So, it is absolutely clear that it would not be fair for biological males to compete in the female category."

The new policy faced immediate pushback from human rights advocates and some experts in the field, including UC Irvine genetic expert Eric Vilain, who has previously advised the IOC on its inclusion policies.

He told LAist that the new IOC policy ignores women athletes with sex traits that aren't neatly aligned with the gender binary.

" Many of these athletes who were born intersex, they [looked] like a female baby, they were raised as female. They don't necessarily have male levels of testosterone," said Vilain, who said the science isn't settled on what advantage intersex women with a Y chromosome have in sport. " The answer to that is very unclear."

Decades of scrutinizing women athletes

Attempts to define the category of woman in athletic competition are nothing new.

Suspicion over the identity of women athletes started when they entered Olympic track and field competitions in 1928, according to Jaime Schultz, a kinesiology professor at Penn State who studies the history of women in sports.

" Track and field was seen as a masculine sport. The fear was that the sport would either masculinize women or else 'masculine women' might be drawn to the sport," Schultz said. "There was suspicion from the very beginning at the Olympic Games."

In the 1930s, two prominent retired athletes who had competed in women's sports transitioned to become men — exacerbating anxieties about any athletes who did not fit gendered norms.

"In the early 20th century, women’s sports were a source of moral and gender panic," historian Michael Waters, who wrote a book on those athletes, told Mother Jones. "Sports officials saw the idea that an athlete could transition gender as a threat to the binary categories they had built."

This led to the scrutiny of women who didn't fit gendered norms, according to Waters.

Women had to submit certificates from a physician in order to compete in track and field competition by the end of the 1930s, Jaime Schultz told LAist. Then came World War II and after that, the Cold War, when Schultz said suspicions turned to Soviet athletes who were suspected of "masquerading" as women. By the 60s, women in professional sport were subjected to gynecological exams and "naked parades" where they had to show their nude bodies to a panel to prove their sex.

American track star Wilma Rudolph breaks the tape at the finish line for the United States at the 1960 Olympic Games in Rome on Sept. 8, 1960.

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" They ask the women athletes to strip naked and parade themselves in front of these three physicians, who sort of look them up and down and say, 'Yes, you're a woman, you can compete in women's events,'" Schultz said. "The visual inspections [were] humiliating to the women."

Those tactics were abandoned after outcry. That's when genetic testing entered the scene.

How genetic testing began for female Olympic athletes

At the 1968 Winter Games in Grenoble, the IOC began trialing a chromosome test called the "Barr body test," which counted X chromosomes to determine an athlete's sex. But that test was scientifically questioned.

French skier Marielle Goitschel (C), Annie Famose (R), and Canadian Nancy Greene after the slalom at the 1968 near Grenoble, during the Winter Olympic Games when the IOC began trialing a chromosome test for female athletes.

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"The stated aim was to detect male athletes posing as women, though in practice the test excluded women with naturally occurring chromosomal variations," according to a history posted to the IOC website in 2023.

One such athlete was Spanish hurdler Maria José Martínez-Patiño, who went to a competition in Japan in 1985, but forgot her certificate verifying her status as a woman. When she re-took the genetic test, she learned she had a Y chromosome and was barred from competition.

Martinez-Patino had androgen insensitivity syndrome, a condition that causes the person to have "genitals that appear female, but they don’t have female reproductive organs," as NPR reported. Officials determined she did not have an unfair advantage and she was eventually allowed to compete, but the process took years and was publicly humiliating.

Spanish hurdler Maria José Martínez-Patiño, who went to a competition in Japan in 1985, re-took the genetic test and learned she had an XY chromosome and was barred from competition.

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"I knew that I was a woman, and that my genetic difference gave me no unfair physical advantage," Patino wrote in The Lancet in 2005. "I could hardly pretend to be a man; I have breasts and a vagina. I never cheated."

In 1992, the IOC introduced the SRY gene test that will now be re-introduced for the L.A. Olympics, according to Vilain at UC Irvine. That test was abandoned by the 2000 Olympics.

"There was so much outcry from the scientific community because it was also deemed not very ethical with lots of issues of privacy," Vilain said.

The rise of testosterone testing

What rose in place of the genetic testing was a new focus on testosterone levels in women athletes. That started in 2009 with South African runner Caster Semenya, who has differences of sexual development that meant she had higher than typical testosterone levels.

At the track and field World Championships, Semenya faced intense scrutiny from the public and sports officials over her appearance and gender identity. This fervor, recounted in NPR's series "Tested," led the governing body for track and field to require Semenya to take medication to lower her testosterone and implement limits to testosterone levels for female competitors.

Double Olympic champion Caster Semenya (C) in 2024 during her legal battle against regulations requiring female athletes with high testosterone to take medication as she prepares for a May hearing. Semenya is seated with her lawyers Gregory Nott (R) and Patrick Brancher (L).

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That approach, too, has faced criticism from human rights organizations for its disproportionate impact on women from the Global South and the privacy issues it raises.

"A policy that calls for scrutiny of women’s naturally-occurring hormone levels — and, in practice, their bodies for signs of perceived “masculinity” ascribed to testosterone — is a form of policing women’s bodies, and passing judgment on their “femininity” as well as on their sex and gender identity," reads a 2020 report from Human Rights Watch.

The IOC's reintroduction of genetic testing has raised even more questions about the lines drawn around women's sports — and how those lines will be implemented come 2028.

In 1984, 1,610 women athletes underwent a "gender verification test" while in L.A., according to the official report on those Olympic Games. How testing will work this time around, who will pay for it, and what controversies it might unearth are still to be seen.