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From chromosomes to genes
It is known from life descriptions prior to 1900 that sex diversity had long been known even then. At that time, viewing the genitals was the only way to determine a person’s gender (Rousseau 1980). Since then, technical knowledge about the body has increased. However, it remained that the knowledge of the moment determined who was male and who was female. Despite the fact that knowledge increasingly confirmed that sex was not a dichotomy, sex diversity became less accepted: people who did not fit into that imaginary dichotomy were forced to confirm with operations that were not possible before. In doing so, the principle was again and again that with better medical technology, doctors could determine who was really a man or really a woman. And time and again, new knowledge showed that the old views were wrong.
The history of the chromosome makes this painfully clear:
Anyone who has read through the history above will notice that the definition of man and woman through time is highly dependent on state of the art biological and technological research from that time.
Before there was any knowledge of chromosomes and genes, external genitalia was considered: penis = male, no penis = female. Before 1900, assigning a gender to an intersex child was a legal and social problem – in fact, doctors knew as little about intersex as, say, judges or pastors. But with the new knowledge about heredity, chromosomes, and gene, doctors became the experts who could determine a person’s true sex. And as knowledge increased, so did confusion, for each time determining one’s gender was more complicated than expected:
Sex determination throughout the years
- Looking at appearance
- Although this seems like the simplest way, there is a lot of overlap between the sexes. For example, just because men are taller on average than women does not mean that someone who is 6 feet tall is a man. Even from the shape of the skull or pelvis, sex cannot always be determined with certainty.
Penis = man, no penis = woman.2 Speaking in medical terms, men with Klinefelter syndrome have wide hips that can easily be seen as feminine. Due to the influence of testosterone, the body of women with congenital adrenal hyperplasia can have masculine features. For these reasons, the body is not a good indicator of sex.
- Looking at the gonads
- Around this time, anesthesia for children became available. This made it possible to perform surgery and remove the gonads in children. A microscope could then be used to determine whether testicular or ovarian tissue was present.
Testicular tissue = boy, ovarian tissue = girl.3The test is not useful for determining gender because women who have a medical diagnosis of androgen insensitivity syndrome have testes AND in the vast majority of cases have a female body and a female gender identity.
- Looking at the Barr body
- If a cell contains more than one X chromosome, the extra X chromosomes are deactivated. The deactivated X chromosome in cells is visible under the microscope as a dark spot named after its discoverer: the Barr body.
Barr-body = boy, no Barr-body = girl.4The test is not accurate enough to determine sex because women with Turner Syndrome and androgen insensitivity syndrome do not have Barr bodies, whereas men with Klinefelter Syndrome, some men with congenital adrenal hyperplasia and XX chromosomes do have Barr bodies.
- Searching for a Y chromosome
- Although it has been known since 1890 that humans have chromosomes, it has only been known with certainty since 1957 that humans have 46 chromosomes.
Y chromosome = boy, no Y chromosome = girl.5The test is not suitable for determining sex because in different forms of sex diversity women are born with a Y chromosome.
- Searching for an SRY gene
- A 1990 publication introduced a new gene that was confidently called the SRY gene: Sex Determining Region Y (Sex Determining Region [on the] Y-[chromosome]) (Sinclair 1990). It was later found that many more genes than just the SRY gene determine whether a person’s body appears more male or female.
SRY gene = boy, no SRY gene = girl.6The test is not suitable for determining sex because intersex women for instance with a medical diagnosis of androgen insensitivity syndrom also have an SRY gene, without being able to masculinize.
- Measuring hormone levels
- Since all previous methods of sex determination failed, a new approach was adopted in 2011 (Football Association FIFA) and 2012 (International Olympics Committee IOC): the testosterone level of female athletes was not allowed to exceed 10 nmol/l. Women with hyperandrogenism were allowed to compete in women’s competitions only if they underwent medical treatment to lower testosterone levels.7In 2015, the international athletics federation IAAF lost a lawsuit filed by Indian athlete Dutee Chand at the International Court of Arbitration for Sport (CAS) because it could not be scientifically proven that testosterone would actually contribute to improved athletic performance. Despite this, an even lower limit of 5 nmol/l is now used by the IAAF. More than 5 nmol testosterone per liter of blood = boy, less than 5 nmol testosterone per liter of blood = girl.8 The test is not suitable for determining a person’s sex because sensitivity to androgens also plays a role and, furthermore, there is a lot of overlap between men and women – in a study of athletes, 16.5% of men were found to have very low testosterone levels, while 13.7% of women actually had high testosterone levels(Healy 2014).