Our gender is identical to our sex, written in our genes, can be clearly assigned and does not change over our lifetime. That’s what many people say. 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.
US President Donald Trump believes this. During his inauguration in January 2025, Trump said it would be US government policy “that there are only two genders, male and female.”
And in a TV debate two weeks ahead of Germany’s general election on February 23, 2025, conservative candidate for chancellor Friedrich Merz said he sided with Trump in the gender debate.
“That is a decision I can understand,” said Merz.
People who support the concept of “only two genders” often point to biology as the basis for their view that there’s only man and woman, unchangeable and with nothing in between.
Yet the broad scientific consensus now looks different: Sex is a spectrum, say some scientists. You can stick with the picture that 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-and-yang 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! That’s what they teach you in school, but again, it’s not that simple.
Men and women as well as gender-diverse individuals all have these sex hormones in their bodies. Average progesterone and estradiol (the most potent natural estrogen) levels barely differ between the sexes.
If one is looking for binarity in hormone levels, one should rather distinguish between “pregnant” and “not pregnant,” according to a review study on recognized sex characteristics by American psychologists. This is because only pregnant women are far out of the ordinary in terms of estradiol and progesterone compared to all other people.
In children, there is no significant difference in sex hormones. It is not until puberty that testosterone levels in particular go up, so that males on average have more testosterone than females.
However, according to recent findings, this difference was also overestimated for a long time due to a failure of research since testosterone was stereotypically studied only in men and estrogens only in women.
Today, targeted research is being conducted on the hormonal overlap between the sexes. It has also been discovered that hormone levels depend to a remarkable extent on external factors and are not, as previously assumed, purely genetically predetermined.
Expectant fathers, for example, have less testosterone over the period of their partner’s pregnancy. The supposedly female hormones estradiol and progesterone, on the other hand, are produced more when individuals compete for dominance ― a behavior that is stereotypically considered masculine.
What gender is your brain?
There are some differences between the brains of men and women. Men’s brains are larger on average. Individual brain regions also differ in average size, density of connections and type and number of receptors.
However, again, researchers cannot pinpoint the male or female brain. Each brain is quite unique and rather resembles a mosaic with different “male” and “female” parts.
Source : https://www.dw.com/en/even-the-science-agrees-there-are-more-than-two-genders/a-57062033
