Gender Testing Part 3

By Robbert Wijtman

Part three of a three-part article

 

The International Olympic Committee (IOC) reinstated gender testing as of March 26, 2026. The reasons the IOC made this decision and the history of how we got here are covered in Part One and Part Two of this article. The criteria for exclusion from the female category in any Olympic event will be a positive SRY gene test. The SRY gene is normally found on the Y chromosome. It is expressed early in development and induces masculinization of the fetus. Without this gene or a detrimental mutation in it (i.e., an ineffective gene), masculinization will not occur, and the individual will appear female even with an XY chromosome pairing.

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To understand how the IOC currently approaches gender determination, it's important to examine the test now proposed: the Polymerase Chain Reaction (PCR).

The test relies on primers (short, man-made DNA strands) that are roughly 20 to 30 base pairs long. These short DNA sequences bind to a small region of the SRY gene.

In standard testing (such as for genetic sex determination), laboratories design primers to amplify specific short segments of the gene.

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The larger SRY gene, including its promoter (the region that controls when the gene is active) and coding sequence (the part that encodes the protein), spans approximately 400-600 base pairs. For the gene to function correctly and produce the protein needed to induce masculinization of the fetus, the entire gene must be present and intact.

 

The PCR test, however, only requires a specific set of 20 to 30 base pairs to yield a positive result, meaning less than a tenth of the complete gene is needed for detection.

 

World Athletics (WA) reinstated gender testing at their world championships last year (2025). Perhaps we can infer how the testing protocol would work with a large athletic population. WA stated, in a press conference, that, between 40 and 60 athletes who had made their finals at this event, had Differential Sexual Development (DSD). This is out of approximately 2000 finalists. Let us be clear: 2-3% is significantly higher than the DSD rate in the entire population (.02%), as reported by the National Institutes of Health (NIH).

 

Four conditions that we should know about.

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Swyer syndrome: The SRY gene is missing or mutated, so it does not function; individuals develop female physical traits despite having an XY chromosome pattern. This condition is called 46,XY complete gonadal dysgenesis.

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Complete Androgen Insensitivity Syndrome (CAIS): A genetic condition where a person with an XY chromosome makeup cannot respond to androgens (male hormones). While they have functioning testes and produce testosterone, their bodies are completely insensitive to it. Consequently, they develop as females, even though they are genetically male.

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46,XX Testicular DSD (XX Male Syndrome): The SRY gene is translocated to the X chromosome in a 46,XX individual, leading to development as a male with male genitalia and testes, despite being genetically female.

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Ovotesticular DSD: The SRY gene is translocated to the X chromosome, but masculinization is incomplete. Individuals with a 46,XX karyotype contain a mix of ovarian and testicular tissue.

 

46,XX Testicular DSD is of interest. While an XX individual with an intact SRY gene would present as a male, an individual with a non-functional SRY gene would present as a female. That is, if a partial SRY gene (inactive gene) is translocated to the X chromosome, it would not prevent the individual from developing as a female. This genetic female would look female and be female, but might well test positively for the SRY gene. Furthermore, this trait would be passed on to half of that woman's children, both male and female. Moreover, all the females fathered by an affected male would have this trait, and half of any children from any affected female would have this trait. This would be completely hidden. There would be no reason to know. Why and how would we know, until we do.

 

With these genetic conditions in mind, an important question arises: Is there such a concentration of people with these conditions in sports? If WA's numbers are to be believed, yes, there is a greater percentage of DSD individuals in Women's sports.

 

Given these complexities, how can we go forward? We need to realize that this test is flawed. The discoverer of the PCR test, Dr. Andrew Sinclair, stated that he felt the test was a poor indicator of gender. A more comprehensive test is needed. A simple cheek swab karyotype test (the type ancestry sites use) could, and perhaps should, be used as a secondary backup to a positive PCR test. This test will show XX, XY, or other possibilities. This is an ongoing story, and new information is sure to come forward.