Genetic Sex

What is gender? For a long time, we were taught that there are "girls and boys" and that generally girls fall in love with boys and vice versa. Sometimes, boys fall in love with other boys and, probably less frequently, girls fall in love with other girls. In the last ten years, we have been learning many new things about gender, so it’s better to make things a bit clearer. As usual, I’ll try to explain it in my own words.

Before talking about gender, it’s better to clarify some aspects that will help us better define it.
I’d like to start with genetic sex. Simply put, genes are pieces of information found in our body (in the DNA) that are passed down from biological parents to their children. Specifically, genes are located in structures called chromosomes. Humans have 23 pairs of chromosomes in their cells. Why pairs? Because 23 chromosomes come from the mother and 23 from the father, and when these pair up, they form 23 pairs.
Out of these 23 pairs, one pair is responsible for genetic sex.

The sex chromosomes can have the form of X or Y. When the pair that forms is XX, typically a female is born, and when the pair is XY, typically a male is born.
But does it always happen like this? No, sometimes the chromosomal pairing phase does not lead to the two typical results I just described: XX and XY.

Some examples include cases where the X chromosome fails to pair with another chromosome (Turner syndrome) or where there is a triplet XXY (Klinefelter syndrome). What happens in these cases? Development is no longer typical, and even though the person may "look like" a female or male, some things are not as we commonly know them—for example, breast development, testicular development, fertility.
So how do we define gender in these cases? We will get to that little by little.

Sources:

• Pinel, J.P.J & Barnes, S.J. (2018) - Biopsychology

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