Gender identity: The sameness, unity, and persistence of one’s individuality as male, female, or ambivalent in greater or lesser degree, especially as it is experienced in self-awareness and behavior. Gender identity is the private experience of gender role, and gender role is the public expression of gender identity.
Gender role: Everything that a person says or does to indicate others or to the self, the degree that one is either male, female, or ambivalent. It includes, but is not restricted to sexual arousal and response. Gender role is the public expression of gender identity, and gender identity is the private experience of gender role.
Gender identity/role: The term used to express the unity of gender identity and gender role which are opposite sides of the same coin. Gender identity and gender role both belong to the self. One’s own gender role is not synonymous with a socially prescribed or conventional gender role stereotype, even though it in some greater or lesser degree reflects this stereotype.
Gender identity/role differentiation: The differentiation of gender identity/role is the product of the interaction of prenatal (phyletically prescribed) and postnatal (social-environmentally prescribed) determinants or events, the latter outweighing the former in their overall influence.
Psychosexual differentiation: A term which historically antedates the term, gender identity/role differentiation, and which is sometimes used synonymously, despite the confusion of its also being used as a synonym for gender identity differentiation.
Genotype: An abstract term referring to the hereditary or gene-determined contribution to individual development. The genotype interacts with the envirotype to produce the uniquely individual phenotype.
Envirotype: An abstract term referring to the environmentally determined contribution to individual development. It interacts with the genotype to produce the uniquely individual phenotype. The term recognizes the fact that substances and events from the environment enter the cells of the body, including the cells of the central nervous system (CNS). There is an intrauterine, antenatal environment as well as a postnatal, extra-uterine one.
Phenotype: The product of the interaction of genotype and envirotype. Both set limits on each other. The genotype, in order to express itself, depends on a favorable envirotype, and the envirotype cannot process what the genotype does not supply.
Critical period: A time-limited phase, specific to a given aspect or phase of individual development, during which a state of sensitivity or readiness of the organism must be met by phyletically specific external stimuli in order to permit that aspect or phase of development to progress optimally. For example, speech cannot be acquired until the sensitive stage is reached, at which time there must be stimulation from hearing other people talk. At the conclusion of the critical period the development which has taken place is likely to remain permanent.
Identification and Complementation: In the differentiation of gender identity/role, identification signifies that an individual establishes a mental schema in the brain by imitating and copying or modeling the behavior of members of one’s own assigned sex. Complementation signifies the mental schema through learning the behavior of members of the opposite assigned sex and through reciprocating with gender-appropriate responses of one’s own assigned sex.