TOKYO (AP) — Japan’s Supreme Court on Wednesday ruled that a law requiring transgender people to have their reproductive organs removed in order to officially change their gender is unconstitutional.

Surprising pattern: The genetic programmes responsible for the development of sex-specific organ characteristics in mammals are turned on almost exclusively late in the development of the organs, in ...

Sex refers to biological differences between males and females (e.g. gonads, sexual organs, chromosomes, hormones). Sex is usually assigned at birth (there are examples when it is assigned later, when ...

What is biological sex? It seems like a question with an obvious answer: male and female, of course. You might point to internal or external sex organs, or sex chromosomes (XX for females, XY for ...

It’s not just about chromosomes. Or reproductive cells. Or any other binary metric. Many genetic, environmental and developmental variations can produce what are thought of as masculine and feminine ...