Deutsche Welle (English edition)
Why sex and gender aren't binary issues
Man and woman with nothing in between, gender as identical to sex ― those who deny the existence of intersex and transgender people like to point to biology. But science actually proves them wrong.
Our gender is identical with our sex, written in our genes, can be clearly assigned and does not change over our lifetime. The woman on one side, the man on the other ― you're either a princess or a knight, with nothing in between. And you certainly have no say in the matter, your sex is what you're born with. Period.
People who think like this usually point to one main argument: That's the science, they say. Biology to be exact.
Yet the broad scientific consensus now looks different: Sex is a spectrum. If you want to stick with the picture, man and woman are at opposite ends, but there's a lot going on in between.
Genetics: Clearly ambiguous
XX chromosomes = female, XY chromosomes = male. This is how sex is formed, we learn in school. In people with XX chromosomes, a vagina, uterus and ovaries normally form in the womb. In XY, penis and testicles are formed.
Clearly, the sex chromosomes are important, but it's not quite so simple.
For example, there are people whose physical traits are female, but they carry the "male" sex chromosomes XY in their cells, and vice versa.
A gene located on the short arm of the Y chromosome, called SRY, determines (along with other players) whether or not testes will form in an embryo. If, for example, this gene is not read due to a mutation, or remains silent, so to speak, no testes will develop despite XY chromosomes.
On the other hand, testes can grow in people with XX chromosomes if the gene jumps over to the X chromosome (presumably during cell division) and is read.
So how sensible is it to determine sex after birth, as is mostly done at the moment, solely on the basis of externally visible sexual characteristics?
Nothing is set in stone
Naturally occurring variations in sex chromosomes are many and varied. This can also have an effect on the visible sexual characteristics, the genitals. Here, too, there are several gradations between the fully formed penis and the externally visible part of the clitoris.
Individuals who cannot clearly be assigned one of the binary sexes refer to themselves as intersex or inter*. The United Nations estimates that 1.7% of the world population belongs to this group. The number is comparable to that of red-haired people in the world.
Since 2018, newborns like this can be registered as "diverse" in Germany. Other countries, such as Australia, Bangladesh and India, also recognize a third sex.
Sex can also change over a lifetime ― or more precisely the gonadal sex identity can. Chinese researchers found this out in a study on mice.
The genes responsible for this change are DMRT1 and FOXL2, which normally balance the development of ovaries and testes in a kind of yin-andyang relationship. When there was a change in these genes, the gonadal sex phenotype could change even in adult animals.
The changing symphony of hormones
Testosterone: The male hormone! Estrogens and progesterone: The female hormones!