Table of Contents
- How many chromosomes does a human have?
- Do all women have two X chromosomes?
- Do all men have one X and one Y chromosome?
- How does a Y chromosome affect development?
- Why was Khelif excluded from the 2023 Boxing World Championships?
- Why can Imane Khelif compete in the Paris Olympics?
- Controversial boxer Imane Khelif: What chromosomes say about gender
In the women's boxing competition at the Olympics in the 66 kg class, Angela Carini of Italy and Algerian Imane Khelif faced off in the round of 16. After a heavy blow to her nose, Carini retired after only 46 seconds in the first round, ending the fight. There were soon discussions about the fairness of the competition between the two, as critics claimed that Imane Khelif did not have two X chromosomes, but one X and one Y chromosome, which is typically found only in men.
Khelif, it is clear, was born a woman (for more information about Khelif and her case, see here). There is no official confirmation that Khelif has a Y chromosome. However, it is possible that women can also have a Y chromosome, and we explain what this means for physical development.
How many chromosomes does a human have?
In general, every human has 46 chromosomes. Men typically have 22 pairs of chromosomes plus one X and one Y chromosome. Women typically have 23 pairs of chromosomes, including two X chromosomes.
Do all women have two X chromosomes?
No, women can also carry both an X and a Y chromosome and may still be able to have children. Additionally, about one in every 1,000 girls is born with three X-chromosomes (trisomy X). Some of these women may be able to have genetically normal children.
Do all men have one X and one Y chromosome?
No, there are men who have an additional X chromosome in their DNA, in addition to one X and one Y chromosome. This is known as Klinefelter syndrome, which affects about 1 to 2 in 1,000 boys born, or about 600 boys per year in Germany. In 80% of cases, this genetic peculiarity is not recognized. Affected individuals are often infertile. The reverse case also exists: the combination of XYY occurs in about 1 in 1,000 boys born.
How does a Y chromosome affect development?
The Y chromosome normally causes an embryo to develop into a male. This is due to the sex hormone testosterone, which is produced more strongly in the presence of a Y chromosome. However, women with two X chromosomes also produce testosterone, but in much smaller amounts than men with X and Y chromosomes. Like in men, it stimulates muscle growth. Additionally, testosterone is a precursor to female sex hormones like estradiol.
Why was Khelif excluded from the 2023 Boxing World Championships?
It is not entirely clear why Imane Khelif was excluded from the 2023 Boxing World Championships in New Delhi after the fact. There are different statements about this. According to the responsible boxing federation IBA, the boxer was physically superior to her opponents based on two tests and therefore did not meet the requirements for a fair competition.
The International Olympic Committee (IOC) relies on a different rulebook than the boxing federation IBA and allowed Imane Khelif to participate in the Olympic Games. The same applies to Taiwanese boxer Lin Yu-Ting. Despite being disqualified at the 2023 World Championships in New Delhi, she is also permitted to compete at Olympia in the featherweight category (up to 57 kilograms).
In the context of the discussion about her eligibility, some critics questioned if Imane Khelif, the Algerian boxer, actually has two X chromosomes due to her physical strength. However, Khelif was born a woman, and while there are no official confirmations about her chromosomes, it is known that women can also carry a Y chromosome.
Despite the controversy around her chromosomes, Imane Khelif was allowed to compete in the women's boxing competition at the Paris Olympics in the 66 kg class, while her Taiwanese counterpart, Lin Yu-Ting, was also permitted to participate in the featherweight category (up to 57 kilograms) at Olympia, despite being disqualified at the 2023 World Championships due to different rulebooks between the IOC and the boxing federation IBA.
