As gleaned from Rethinking Gender by Robin Marantz Henig:
We have learnt that sex chromosomes determine a baby’s sex: XX means its a girl and XY means its a boy. However, there are exceptions to the general rule.
First, when the SRY gene is missing or dysfunctional:
An XY embryo fails to develop male anatomy and is identified as a girl at birth, or an XX embryo develops male anatomy and is identified as a boy at birth.
Second, when one has complete androgen insensitivity syndrome (CAIS):
An XY embryo’s cells respond minimally, if at all, to the signals of male hormones. Even though the protogonads become testes, and the foetus produces produces androgens, male genitals don’t develop. The baby looks female, with a clitoris and vagina.
In one case, parents lied to their 17 year old that she had to remove precancerous ovaries when she in fact, had her undescended testes surgically removed.
Third, when an enzyme that converts testosterone into potent hormone DHT is missing:
When the DHT is absent, the tubercle in the embryo becomes a clitoris. The baby looks female and is raised as a girl. However, during puberty, which requires only testosterone and not DHT, the child turns into a man. What at first appeared to be a clitoris grows into a penis.
At the end of the day, we realise that some people face a lot more confusion in their lives than we ever will; and life goes on.