Biological Gender Identity

Gender is defined as “the complex interrelationship between an individual’s sex (gender biology), one’s internal sense of self as male, female, both or neither (gender identity) as well as one’s outward presentations and behaviors (gender expression) related to that perception, including their gender role” (Gender Spectrum, 2015). What this means is that societies and cultures have a set of norms that attempt to classify gender by outlining which characteristics and behaviors are associated with males and which characteristics and behaviors are associated with females. However, in all societies, there are some individuals who do not identify with the aspects of gender that are assigned to their biological sex (World Health Organization, 2015).

From a biological standpoint, typically our genes dictate whether we will be male or female at birth and anatomy plays a key role for many in gender identity. However, hormone exposure in utero directs the development of male or female genitalia of the embryo and sex differentiation in the fetal brain. Thus, maternal hormones are paramount to the sexual development of the fetus. Fetal gonad development is dependent on the amount of androgens present at 6 – 12 weeks gestation. If the level of androgens is high, particularly the level of testosterone, male genitalia develop. On the other hand, if the level of androgens is low or absent, the result is female genitalia. After this physical distinction has transpired, sex differentiation within the brain of the fetus follows and the health of the maternal endocrine system impacts the outcome. The primary function of the endocrine system is the release of hormones, including the testosterone mentioned previously. If there is an issue with the maternal endocrine system, it can cause abnormal sex differentiation of the fetal brain which results in abnormal gender-specific behavior (Vliet, 2003). Because the development of the genitalia occurs separately from sex differentiation in the fetus, genital masculinization or feminization may not always match the masculinization or feminization of the brain (WHO, 2015). Therefore, one may appear anatomically as a male or female yet identify as and behave as the opposite