This is the third part of a series about the complex biological realities of sex. Though the posts build on one another, each can be understood alone.
In previous posts in this series, I’ve talked about what sex is, and the many ways it can manifest in human bodies. But what determines whether an individual is male, female, or something else altogether?
I’m talking here about the spectrum of sexed bodies that exist in nature, not gender identity, because only humans can have gender. Gender is created by institutions, culture, and human relationships. As far as we know, non-human animals don’t have cultural constructs of male and female. But they do have an amazing variety of sexes and paths to determine what sex an animal will be.
You may have learned that sex determination in humans comes from the sex chromosomes: two X chromosomes will lead to a human with ovaries and a uterus, and an X and a Y chromosome will lead to a human with testes and a prostate. This is not entirely true, but gonadal sex (whether your body is equipped to make eggs or sperm) is indeed genetic in humans. But in many animals, sex determination is environmental, not genetic.