Gender inequality refers to unequal treatment or perceptions of individuals based on their gender. It arises from differences in socially constructed gender roles as well as biologically through chromosomes, brain structure, and hormonal differences. Gender systems are often dichotomous and hierarchical; gender binary systems may reflect the inequalities that manifest in numerous dimensions of daily life. Gender inequality stems from distinctions, whether empirically grounded or socially constructed. (On differences between the sexes, see Sex and psychology.) Keep reading
http://en.m.wikipedia.org/wiki/Gender_inequality