This article was contributed by Amanda Nottke.

Recent headlines have accused the 2009 World Championship runner Caster Semenya of being a hermaphrodite and therefore ineligible for her 800 meter gold medal. Is she really a hermaphrodite, and would her condition conceivably give her an advantage over other “normal” women?

Gender Testing in Sports

The segregation of athletic events into men’s and women’s divisions has led to a history of high-performing women falling under suspicion of being men in disguise. On rare occasions men have deliberately passed themselves as women in order to compete. One such example occurred in 1936, when the female Jewish high-jumper Gretel Bergmann was dropped from the German team and replaced at the last minute by Dora Ratjen instead. Ratjen placed fourth, but two years later was revealed to in fact be Herman Ratjen, who claimed he had been forced by the Nazis to live and compete in female disguise for three years. Instances like this have contributed to the fear that male athletes would disguise themselves as females in order to gain an unfair advantage, leading in turn to mandatory gender testing of female athletes for a period beginning in the 1960s. This practice was officially halted by the International Olympic Committee in 1999.

Much more common however, are instances of intersex competitors, who may or may not even know that they are different than the majority of women. It may seem surprising that a person could reach adulthood believing she is a woman when the athletic world defines her as a man, but it is possible and more common than one might expect. Part of this has to do with the way gender is determined in sports, where a combination of genetic testing and physical exams are used to determine gender. Gender is a term which can be defined in many different ways, but as it pertains to gender testing in athletics it can be considered equivalent to biological sex.

Male, Female, or Some Combination of Each?

How do you define gender? If a person has two X chromosomes, functional female reproductive organs (the ovaries) and female secondary sex characteristics such as breasts and a vagina, then we would all agree that this person is both genetically and phenotypically (physically) a woman. But what about a person with unknown sex chromosomal status, a vagina and undescended testes, as some news sources have reported is the case for Caster Semenya? If these news reports are in fact accurate, then Caster Semenya is not a true hermaphrodite (as defined as a person with both ovaries and testes), but she may well be “intersexed”.

Intersex conditions can be loosely defined as any atypical combination of male and female traits, including ambiguous genitalia. One way to understand intersex conditions is to appreciate human sex development and realize that we all started out with ambiguous gender.

During normal development, regardless of gensemenya picetic sex (which is determined by the sex chromosome contribution of the sperm), the fetus develops primitive gonads around six weeks of age. These tissues will further develop into either ovaries or testes, depending on the genetic sex. The XY-containing fetus will develop testes that begin secreting the hormone testosterone around week 8, and the testosterone inhibits further development of female sex organs and promotes the development of the male sex organs. In the absence of testosterone, the XX-containing fetus develops female sex organs.

From this description of normal development, we can see that one cause of intersex conditions can be problems with hormone production or sensitivity. If you are an XY-containing fetus with testosterone-producing testes but you have a mutation in the androgen receptors that respond to the hormone, then you are effectively “deaf” to the testosterone and will develop outwardly female.

One example of this is Androgen Insensitivity Syndrome, or AIS, caused by a mutation in the androgen receptor gene. Depending on the severity of mutation in the androgen receptor, the genetically XY person can range from a male with reduced fertility to having a female body with internal testes instead of ovaries and a uterus, similar to what has been reported about Caster Semenya.

Caster Semenya is Not Alone

The details of Caster Semenya’s condition have not been fully reported to the media, at least from a reliable source, so we cannot speculate on which (if any) type of intersex condition she is experiencing, and whether her condition would give her any advantage over other women. As described above, it is completely possible for an XY genetically male person to develop as outwardly female and virtually indistinguishable from an XX-containing female. If this is the case for Semenya or other intersex athletes, than despite their genetic male sex, these athletes have no advantage over their competition. The issue can be more complicated, because depending on the individual situation an intersex person may have more traditionally “male” characteristics, such as increased muscle mass, which might well give her an advantage. So how can we make athletic competitions fair for everyone?

On the one hand, Semenya is 17 years old and was gender-tested without her knowledge or consent, so it is inappropriate for anyone to demand access to her medical record, especially the world-wide media. On the other hand, there are clear differences in athletic abilities between men and women, so sports authorities can reasonably demand some clarification on an athlete’s gender. Traditionally, it appears that genetically XY women have been disqualified based on the assumption that their testosterone gives them some advantage, but medically we know that this is not always the case. In the case of AIS and similar conditions, the body’s inability to respond to testosterone means that the XY woman can therefore get no athletic benefit from her testosterone, so why should she not be allowed to compete in women’s events? Ideally, some compromise could be struck where each person’s gender is determined individually and in the context of not just the genetic sex but the phenotypic (or physical) sex, so that all athletes (male, female and intersex) can have a fair chance to compete.

Regardless of what happens to her gold medal, Semenya may find herself a spokesperson for intersex people, an under-represented group which is bigger than you might expect. Approximately 1 in 100 babies have ambiguous genitalia at birth, and 1 in 10 of those babies (0.1% of all babies) is physically ambiguous enough to require a specialist’s attention. So although you personally may think your sex and gender are quite obvious, you almost certainly know someone whose status hasn’t always been clear.