n all societies the obvious biological difference between men and women is used as a justification for forcing them into different social roles which limit and shape their attitudes and behavior.
That is to say, no society is content with the natural difference of sex, but each insists on adding to it a cultural difference of gender. The simple physical facts therefore always become associated with complex psychological qualities. It is not enough for a man to be male; he also has to appear masculine. A woman, in addition to being female, must also be feminine. However, once the contrast between men and women has been increased and accentuated in this fashion, it is usually taken as a further manifestation of biological differences which confirm the need for different social roles. Or, to put it another way, sex differences are used to create gender differences which are then explained as sex differences which, in turn, require gender differences, and so on.
This may be no more than circular reasoning, but it is socially very effective. For example, in our own patriarchal society males enjoy a socially dominant position. Thus, from an early age, boys are helped to acquire a masculinity that allows them to assume and maintain that position. By the same token, girls are taught to cultivate a submissive femininity. The resulting difference in the male and female character is then described as inborn and used to defend the existing power arrangement.
Only those who accept it are normal, and only they can expect to succeed. The male social role is designed to reward masculine men, while the female social role offers its relative advantages only to feminine women. (The aggressive man will run the bigger business; the pretty, agreeable woman will find the richer husband.) In other words, masculinity and femininity are gender qualities which are developed in response to social discrimination. However, once they have been developed, they justify and cement it.
The masculine and feminine gender roles mutually reinforce each other and thereby perpetuate the inequality on which they are based.