The genders are different because their brains are different. The brain is differently constructed in men and in women; it processes information in a different way, which results in different perceptions, priorities and behaviour. Men and women are equal only in their common membership to the same species, humankind.
The influence of testosterone on the prenatal brain is producing differences in personalities and social behaviours of this humankind.
The extraordinary journey from the sexual differentiation from the prenatal brain to the gender differences inherent in kindergarten play styles, classroom abilities and adult attitudes towards love, sex and marriage and social life in general have been analysed within the last 20 years.