Simply knowing that an individual is female or male implies they will have certain physical and psychological traits and even participate in particular kinds of activities. Gender stereotypes define our culturally agreed upon notions of gender appropriate behaviors. These behaviors are enforced by self and others. Gender differentiation begins at birth. Female infants are dressed in pink and their rooms are decorated in pastels.
Parents give subtle messages regarding gender and what is acceptable behavior for each gender.
As children move into the larger world of friends and school many of the ideas and beliefs are reinforced by those around them. Conformity is a major factor in human behavior. This notion adds support to maintaining the idea of gender differentiation. Traits associated with males tend to be more highly regarded than traits associated with females. This may help to explain why it is easier for females to cross-over the gender stereotype barriers and harder for males to do so.