Gender Identity

Gender identity is commonly defined as an individual's sense of being a male or a female. Formany, gender identities are aligned with physical sex characteristics including hormones, chromosomes, genitalia, and secondary sex characteristics, as well as with sex assignment and gender roles. For others, gender identities do not match one or more sex or gender traits. Several variations on this concept of gender identity exist. For example, the social identity perspective defines gender identity as the degree of awareness and acceptance of one's own gender category. Alternatively, symbolic interactionists consider gender identities as self-concepts based on fulfillment of gender roles.

Multidimensional models of gender identity illustrate the complexity and breadth of gender identity. For example, Susan Egan and David Perry offer a model of gender identity including five components: (1) knowing one's gender category membership, (2) feeling similar to others in one's category, (3) feeling satisfied with one's gender assignment, (4) feeling pressure to conform to gender roles, and (5) believing that one's gender category is superior to the other category.

Several stage models of gender identity development connecting gender knowledge to gender behavior have been proposed by researchers such as Lawrence Kohlberg, Warren O. Eaton and Donna von Bargen, and Phyllis Katz. Most models suggest that gender identity development is initiated by acquiring the ability to label the self and others with correct gender labels. Next, children learn that identity is stable throughout development and is permanent regardless of the influences of culture, motive, or hairstyle or clothing changes. Katz proposed that sexual gender, developing during puberty, and reproductive gender, developing during adulthood, also contribute to gender identity. To date, research has failed to clearly support or refute any of these models.

Evidence supports both biological and sociocultural influences on gender identity. While sex may be defined by sex chromosomes (XY for male and XX for female), sex chromosomes direct gonads to develop into testes or ovaries, which, in turn, produce the hormones between weeks 8 and 24 of gestation that influence gender development. Prenatally, testes produce testosterone, whereas ovaries do not produce considerable amounts of the hormone. Studies of girls with a congenital adrenal hyperplasia (CAH) illustrate the effects of prenatal hormones on gendered behaviors. CAH is a condition in which fetuses are subject to large quantities of hormones due to synthetic steroids. Girls (XX) with CAH are born with masculinized genitalia and undergo hormone treatment and surgical feminization, whereas boys (XY) with CAH are born with normal genitalia. As children, boys with CAH exhibit play behavior and interests similar to non-CAH boys, whereas girls with CAH exhibit play behavior and interests that are more masculine than that of non-CAH girls and slightly more feminine than CAH and non-CAH boys. Considering postnatal hormonal and environmental influences on CAH and non-CAH girls were similar, these behavior differences may be attributed to prenatal hormonal environments.

A second surge of hormones from the testes occurs shortly after birth, from the first to sixth month, increasing testosterone in boys but not in girls. These early postnatal hormones also influence gender identity development. In animal studies, when male animals are castrated and female animals receive hormones during this critical period, sex-typed behaviors are completely reversed in adulthood. Additionally, brain structure may be connected to gender identity. For example, male to female (MTF) transsexuals have been observed to have a smaller subsection of the hypothalamus than a male control group.

...