Someone’s sex is determined at birth. It’s only based on what doctors visually perceive at birth and is then indicated on a birth certificate. Doctors use norms on how a body is supposed to look to register it as a boy or as a girl. Sex is determined by physical characteristics. The western binary model assumes two sexes: man and woman, both with well-defined and distinct sex characteristics. Those two groups are a part of the broad sex characteristics spectrum, but there’s a lot more bodily variation. People with sex characteristics that don’t fit in the traditional binary of man/woman have intersex bodies.
