If a society puts half its children into short skirts and warns them not to move in ways that reveal their panties, while putting the other half into jeans and overalls and encouraging them to climb trees, play ball, and participate in other vigorous outdoor games; if later, during adolescence, the children who have been wearing trousers are urged to “eat like growing boys,” while the children in skirts are warned to watch their weight and not get fat; if the half in jeans runs around in
sneakers or boots, while the half in skirts totters about on spike heels, then these two groups of people will be biologically as well as socially different. Their muscles will be different, as will their reflexes, posture, arms, legs and feet, hand-eye coordination, and so on. (…)
There is no way to sort the biological and social components that produce these differences. We cannot sort nature from nurture when we confront group differences in societies in which people from different races, classes, and sexes do not have equal access to resources and power, and therefore live in different environments.
— Ruth Hubbard, The Political Nature of “Human Nature”