This might sound like a silly question, but what chromosomes determine whether a human is born a boy or a girl? I ask this because I got https://embryo.asu.edu/pages/sex-determination-humans when googling the subject and it contains the word "typically" in places I did not expect. For example:
Humans typically develop as either male or female
Humans who inherit two X chromosomes typically develop as females, while humans with one X and one Y chromosome typically develop as males.
Because females tend to only have X chromosomes, the egg cells that they produce typically carry an X chromosome
Is this a form of political correctness, or are there legitimate cases that justify the insertion of the word typically? I'm genuinely curious what these exceptional cases might be.