Our boys and girls form their gender characteristics through their experiences and relationships. Violent play is not a primal, hard-wired characteristic of boys. It is an experience that forms their characteristics through brain plasticity. Different boys and girls have different large muscle needs. Large muscle needs do not necessarily translate to a love of playing at violence.

“Instead of simply dividing their subjects by biological sex, they also gave each subject a test of psychological “gender:” a questionnaire that assesses each person’s degree of masculinity vs. femininity – regardless of their biological sex – based on their interests, abilities and personality type.

[ . . . ]

“Yes, men and women are psychologically different and yes, neuroscientists are uncovering many differences in brain anatomy and physiology which seem to explain our behavioral differences. But just because a difference is biological doesn’t mean it is “hard-wired.” Individuals’ gender traits – their preference for masculine or feminine clothes, careers, hobbies and interpersonal styles – are inevitably shaped more by rearing and experience than is their biological sex. Likewise, their brains, which are ultimately producing all this masculine or feminine behavior, must be molded – at least to some degree – by the sum of their experiences as a boy or girl.”

read the article at scientificamerican.com