Gender is a socio-psychological characterization of being a man or a woman. Gender identity is the feeling of being identified as one of these genders, and it is usually established before the age of three. Gender role describes society's expectations of how a man or woman should behave based on their gender. Biology is the natural factor in differential development between the sexes, and biologically, a person with 46 XY chromosomes in their cells and the gonads of the testes would be a male, and a person with 46 XX chromosomes in their cells and the gonads of the ovaries would be a woman. Additionally, hormones such as testosterone and estrogen, as well as evolution, offer insight into psychological differences between the sexes (Santrock, 2009). However, there is growing evidence that gender roles and stereotypes are taught from childhood, and studies highlight that teaching gender roles at an early age greatly affects a child's identity as to its sex and the opposite sex. Through parents' toy choices, children learn what is appropriate and inappropriate for their gender (Wood, Desmarais, & Gugula, 2002). Although boys have a strict set of rules and expectations for their role in society, girls' roles are not as consistent. This factor causes gender conflicts in girls and causes problems with boys because they are very limited in what they can do (O'Brien, Peyton, Mistry, Hruda, Jacobs, Caldera, Huston and Roy, 2000). These roles and expectations are taught not only by parents, but also through children's books and media. One of the main problems with teaching gender roles too early is that children develop the concept of gender stereotypes. Gender stereotypes are culturally defined, which typically dictates men to be... middle of paper ....... Galligan, S., Barnett, R., Brennan, M., & Israel, G. (2010). The effects of gender role conflicts on the resilience of adolescents and emerging adults. Journal of Men's Studies, 18(1), 3-21.Gooden, A. and gooden, M. (2001). Gender Representation in Notable Children's Picture Books: 1995-199. Sex Roles, 45(1/2), 89-101. O'Brien, M., Peyton, V., Mistry, R., Hruda, L., Jacobs, A, Caldera, Y., Huston, A. & Roy, C. (2000). Cognition of gender roles in three-year-old boys and girls. Sex Roles, 42(11/12), 1007-25. Tepper, C. & Cassidy, K. (1999). Gender differences in emotional language in children's picture books. Sex Roles, 40(3/4), 265-80. Wood, E., Desmarais, S. and Gagula S. (2002). The impact of parental experience on children's stereotypical toy play. Sex Roles, 47(1/2), 39-49.Santrock, J.W. (2009). Development throughout life. Boston, MA: McGraw-Hill Higher Education.