“Both sociologists and psychologists define gender identity as the differing cultural and social roles that men and women inhabit, as well as the ways in which individuals experience those roles, both internally and in terms of the ways they present themselves to the world through their manner of dress, behavior, physical comportment, and so forth. Both distinguish between a person's biological sex (male or female) and gender identity (masculine or feminine)” (Malti-Douglas, 2007, para.). However, many have argued that anatomical differences between the sexes are the result of historically specific conceptualizations of the body, such that even something as apparently "objective" and "neutral" as biology must be recognized as the product of cultural, social, and historical factors (Malti-Douglas, 2007). Biology approaches the body with certain assumptions about gender that the sexes constitute complementary opposites, for example exaggerating whatever physiological differences may exist between male and female (Malti-Douglas, 2007). Hence, transgender advocates offer a related claim, arguing that the designation of two sexes is itself arbitrary, given the reality of human biological variation (Malti-Douglas, 2007).
Biological Factors- Nature
Women and men are chromosomally different. Women have two X chromosomes (XX), whereas men have an X and a Y chromosome (XY) (Sammons, 2013). In the period following conception, female and male embryos are indistinguishable apart from their chromosomes (Sammons, 2013). However, the Y chromosome in males starts to promote the production of testosterone and other androgens (male sex hormones) (Sammons, 2013). These androgens cause the male to develop testes and a penis instead of ovaries and a uterus. The androgens also cause the male brain to develop differently from the female. A bio psychologist would argue that it is these differences in brain development, and the differences in brain activity caused by the secretion of androgens in adulthood, that cause men to behave differently from women (e.g. acting more aggressively) (Sammons, 2013). Gender identity emerges by the age of two or three and is influenced by a combination of biological and sociological factors reinforced at puberty (Krapp & Wilson, 2006). Once established, it is generally fixed for life. Aside from sex differences, other biological contrasts between males and females are already evident in childhood. Girls mature faster than boys, are physically healthier, and are more advanced in developing oral and written linguistic skills (Krapp & Wilson, 2006). Boys are generally more advanced at envisioning and manipulating objects. They are more aggressive and more physically active, preferring noisy, boisterous forms of play that require larger groups and more space than the play of girls the same age (Krapp & Wilson, 2006).
Women and men produce different sex hormones in varying quantities. Besides affecting the functioning of various bodily organs (e.g. causing the menstrual cycle in women) these sex hormones appear to have an effect on behavior (Sammons, 2013). Testosterone, which is produced in greater quantities by men, affects several types of behavior, some of which are regarded as ‘typically male’. For example, Dabbs et al (1995) found that violent offenders had higher testosterone levels than non-violent offenders and Coates et al (2008) found that financial traders with higher testosterone levels took greater risks (Sammons, 2013). Women have higher levels of oxytocin than men. Some researchers have linked this to increased sociability. Oxytocin seems to affect the formation of bonds and attachments between people and Klaver et al (2009) found that higher levels of oxytocin are linked to improved memory for faces (Sammons, 2013).
There are many biological factors that determine gender identity;