The most common definition of biological sex is based on physical structure or morphology, but some definitions also include chromosomes. The two types of biological sexes are called phenotypic gender and genotypic gender, respectively. There are a very small number of people whose two types of gender are different from each other, which can cause some confusion. It is necessary to point out in what situations each of the two gender types should be used. Phenotypic gender is almost always the same as the gender assigned at birth because it is easy to determine. If a person's genotypic gender differs from it, he or she will grow up and participate in various activities without knowing it throughout his or her life (unless genetic testing is done). It is the genotypic, not phenotypic, gender that determines secretion of hormones, including testosterone and estrogen, determines some physical attributes, muscle mass, explosive power, etc.
Therefore, for people with the two types of biological sexes having different values, when gender must be specified, different gender types should be used for different occasions. For example, phenotypic gender is often used for surgery, genotypic gender for prescriptions, and should also be used for registration for sports events from now on. The International Boxing Association (IBA) determines gender by genotype. In a letter to the International Olympic Committee (IOC) in June 2023, they pointed out that Algerian boxer Imane Khelif had XY (male) chromosomes in two separate tests, and therefore disqualified her (him) from participating in the 2023 International Boxing Championships. The letter stated, "This situation epitomizes the importance of protecting safe sport, and the integrity of sport in which the Olympic Movement is jointly committed to." Unfortunately, the IBA did not disclose the test results. Meanwhile, the IOC accused the IBA of defaming the IOC. As a result, the IBA's test results were ignored by the IOC, and some athletes who may have XY chromosomes are allowed to participate in the women's events of the 2024 Olympics. It is regrettable that as a tradition, the Olympic Committee still determines gender based on the sex assigned at birth, i.e. phenotypic gender. For the very few who have a different phenotype from their genotype, XY chromosome athletes clearly have a greater advantage in participating in women's events. (Similarly, athletes with XX chromosomes but of phenotypically male gender are at a disadvantage in participating in men's events, although this may never actually happen, for obvious reasons.)
The cost of sex chromosome testing is currently as low as $50, and the average price per person may even be lower if we exempt the athletes who were tested before and exclude certain events that do not need this test. In four years, the Olympic Committee rakes in $7.6 billion. With this income, XY/XX chromosome testing on participating athletes should be routine. The ancients did not know about genes, much less the fact that it is genotypic gender that determines the male hormones which boosts performance in competitive sports (they didn't know because in most cases, this gender is the same as phenotypic gender). But in the second decade of the 21st century, it is high time we corrected this mistake. After all, unfairness in women's competitive sports caused by the XY chromosomes of the few is no less than or perhaps even greater than doping. In sports of body contact such as boxing, there is an added layer of concern, that is safety of the athletes.
Let me reiterate. There are two types of biological sexes. It's horrible to say that biologically male athletes should not compete with female athletes. We must say genotypically male, or as British biologist Dr. Richard Dawkins said, "genetically male boxers should not fight women" (my italics). Dr. Dawkins's Facebook account was deleted because he didn't make it clear to agitated readers as well as muddle-headed Facebook censors that his word "genetically" must not be replaced with the ambiguous "biologically", as those supporting or condemning him did. Once this distinction is made, it becomes clear that we are only advocating the unambiguous definition of gender based on genotype for competitive sports only, leaving the choice of the type of gender, genotypic or phenotypic, alone in other aspects of life. And at the same time, we should respect those people who have one type of gender different than the other, unconditionally in all circumstances. They are one type of intersex or bisexual people, but they are normal human beings just like everyone else.
