Brains vary in the degree of being lateralized. Both males and females go from less lateralized (which I will take as indicating the potential for androgeny) to strongly lateralized male and female patterns. While I am focusing on brain differences, these very differences contribute over time to cultural normative behaviors, especially the expression of masculinity/femininity, the expression of emotions and the facilitation/resolution of cooperation, all under the old rubric of manners. Male and female cultural stereotypes are just that and mask still many differences in brain structure and function. So early on in gestation, the fetal brain is essentially female. Both sides of the brain are engaged with the current concrete situation, i.e., the immediate stimuli fields impinging on the sensory organs internal and external. When lateralization begins, brains start to specialize higher level functions, the right to continue its focus on the here and now as the left begins to separate out old from new in a special way where old can stretch very far back and the new include self generated visions, plans and fantasies. As infants become children the process of lateralization extends to the cerebral hemispheres, the highest brain structure (so far?) and we see the emergence from the biological roots of humanity of empathy (right) and symbolization (left). Next up, the corpus callosum and the first pinnacle of our maturation.