Watching the 2024 Paris Olympics reminded me of my intense love for sports. It is the nobility, beauty, strength, agility, and fairness that attract me and the audience. Performances by Simone Biles, with her majesty and strength, to Katie Ledecky’s’ power and domination, surrounded by Olympic and world record performances, often bring me to tears. These attributes have abounded in Paris, but unfortunately, something foul is also afoot.

Sexual and gender identity disorders (SGID) are a relatively rare group of medical conditions. As with most medical subjects, the science and biology of these conditions are complex. Using genes, hormones, and the presence or absence of reproductive organs, endocrinologic and embryologic textbooks devote multiple chapters and extended pages to SGID and its subtypes. Various categories use terms such as transgender, hermaphrodite, intersex, sexual dysphoria, and disorders of sexual development (DSD), characterizing and dividing these rare cases. The latter category, DSD, describes individuals with a contradiction between the karyotype or genes, hormone levels, and the appearance of their reproductive organs. SGID individuals with a male genotype who compete in women’s sports are the subject of this blog.

While these conditions are rare, many SGID individuals have the desire and talent to perform in certain sports and compete on the world stage. Those SGID individuals with a male genotype and biology often choose to be identified as a woman but perform as a man. These individuals tend to dominate their field when included in female competition. This is to be expected, as these individuals have male biology, which predicts a stronger, faster, and often more aggressive individual. When these athletes compete against women in contact sports, injury is possible.

Transgender athletes are those individuals assigned at birth as male, who have a male XY genotype or genetic profile but, because of gender dysphoria, choose to be considered female. Some choose to have gender reassignment treatments and surgeries. Renee Richards is perhaps the most well-known. She played professional tennis in the 1970s after sex reassignment surgery. Lia Thomas is a contemporary transgender woman who competes in competitive swimming.

In the boxing arena at the Paris Olympics, two DSD individuals have competed. Imane Khelif is an Algerian boxer; Lin Yu-ting is Taiwanese. Both were successful in securing a medal in their respective weight classes. Infamously, Imane Khelif’s opponent vacated her match after being humiliated on international television.

In 2022, North Carolina volleyball player Payton McNabb suffered a serious injury after a trans-identified male player spiked a ball at her head and rendered her unconscious. Last year, a trans-identified male opponent injured a female athlete during a field hockey game in Massachusetts when a ball he threw at her knocked her teeth out. Examples of other females being injured by males taking part in overseas or semi-professional women’s sports abound, occurring in soccer, rugby, hockey, and mixed martial arts.

Promoting fair and equal treatment in all female sports is something I strongly advocate. I am a proponent of the Title IX Education Amendments of 1972. Society should promote female sports. The presence of SGID individuals in female sports does not promote fair competition. Genetic and endocrine male biology predicts an unfair advantage for the SGID individual.

Besides an unfair advantage in SGID female competitions, injury is often the result. Injury can be psychological as well as physical. Losing, especially on the international scene, can humiliate, as with Imane Khelif’s boxing opponent. Reilly Gaines’s televised loss to Lia Thomas in the swimming pool is another example of the sport’s encouragement of humiliation. Gaines has talked openly about her feelings. Her advocacy on this subject is essential.

Physical injury has continued to occur. Future death in the sporting venue is only one ill-timed punch away.

Do we want to treat our women in this manner? Ask yourself, would you like your daughter competing against a biological male, risking defeat, humiliation, and injury? I feel compassion for the SGID athlete, but allowing this situation to continue is not the answer.

I envision a separate league for SGID competition. This is much like the para-athlete leagues and would allow for a fair playing field. Everyone should be able to enjoy athletic competition. However, fairness and safety are of paramount concern.

William Lynes is a urologist and author of A Surgeon’s Knot.