Gender is a complex social construct based upon biological sex, but it is not the same as sex. It can also be argued that gender alone drives us, and that sex is an incidental feature.

Gender facilitates sexual interaction and reproduction. Gender is intertwined with identity, expression, presentation, relationships, child-rearing, societal role and structure, pairing, games, and eroticism. We are a sexually dimorphic species, where physical appearance is the number one gender marker.

Gender becomes fixed in infancy, but it remains remarkably fluid, full of twists and surprises.