Because biology is far more complicated than the binary presence of an X or Y chromosome. The easiest way to explain this is that being intersex also exists in

Because biology is far more complicated than the binary presence of an X or Y chromosome. The easiest way to explain this is that being intersex also exists in biology: https://en.m.wikipedia.org/wiki/Intersex_(biology) https://en.m.wikipedia.org/wiki/Intersex_(biology)