Most children learn to categorize themselves by gender by the age of three. From birth, in the course of gender socialization, children learn gender stereotypes and roles from their parents and environment. Traditionally, boys learn to manipulate their physical and social environment through physical strength or dexterity, while girls learn to present themselves as objects to be viewed. Social constructionists argue that differences between male and female behavior are better attributable to gender-segregated children's activities than to any essential, natural, physiological, or genetic predisposition.