Gender is biological, the level of testosterone in an individual determines this

Testosterone is a significant biological chemical contributing to mammalian development. Early levels of exposure to it determines permanent behaviour. Higher levels of testosterone is predominantly present in males, generating some of the characteristics associated with gender stereotypes such as choice of toys as children and sexual orientation. The variation in the levels of testosterone also had an impact, such as in females with high levels of prenatal exposure to testosterone leading to congenital adrenal hyperplasia (“CAH”). Women with high levels of prenatal exposure to testosterone who develop CAH have shown more typically male behaviours, such as a preference for stereotypically male toys, more interest in rough play. This behaviour is more present than in the female born without CAH, but not as present as it is in individuals born male. This supports the proposition that gender is biological and not social as the levels of exposure to testosterone prenatally determines male or female behaviours. ^[1]