Biological sex is all over the news lately. Whether it's via President Trump's executive order affecting passport policy, moving trans inmates... How is sex determined? Scientists say it's complicated ...

Claims spread that definitions of "male" and "female" included in a January 2025 executive order that asserted sex is established at conception accidentally classified all Americans as women. The ...

Sex chromosomes are chromosomes, or packages of DNA, that are found inside the nucleus of all of your cells. There are two different kinds: X and Y, which determine whether you’re biologically male ...