A critical dimension of children's early development is the acquisition of differentiated gender identities and the internalization and acceptance of corresponding sex-linked behaviours and roles. The gender identity and roles associated with each sex are not directly based on biological differences, but are culturally and socially constructed over time by a process which starts before birth, but intensifies from birth through the early years into young adulthood. 
Parents and significant others in the lives of infant children create the social environment that begins their initiation into these gender-specific norms, behaviours, and roles. When children enter school, this process is heightened and reinforced by several explicit and implicit factors that have a differential impact on the two exes.