The Science Behind Gender Identity

By Alina Dillahunt

Recently, U.S. politicians in 16 states have proposed bills governing which bathroom transgender individuals are allowed to use. All attempted bills have failed and been met with great opposition. North Carolina’s legislature managed to pass a piece of legislation nicknamed the “bathroom bill,” but it was later repealed [1]. There are various beliefs and opinions surrounding transgender individuals’ identities. Some believe that transgender individuals should be able to use the bathroom of the gender they identify with, or the bathroom they feel most comfortable using. Others suggest that sharing a bathroom with a transgender person may make it unsafe for cisgender individuals, those who identify with their assigned sex. However, there is no evidence that transgender individuals have harmed a cisgender person in a bathroom [2]. Legislation on transgender bathroom use can affect how individuals perceive each other and themselves. Therefore, it can have a significant impact on the lives of the target population. When a lawmaker proposes a bills that does not align with scientific findings, the public may be swayed to also discount or overlook scientific evidence. Therefore, bathroom bills and other legislation impacting transgender individuals should be constructed from research in the fields of social psychology, biology, and endocrinology, instead of scientifically unsupported opinions.

Gender is complex and there are many exceptions to the dual categorization system of male and female. Canonically, a genetic female, possessing XX chromosomes, will have more female hormones like estrogen and progesterone; a genetic male with XY genotype will have more testosterone. Through differences in hormones, chromosomal sex usually leads to corresponding body appearance. However, there are several cases where the chromosomal sex of an individual does not match their hormone production due to various naturally occurring disorders. One such abnormality is congenital adrenal hyperplasia, resulting in females with more male hormones. Another, androgen deficiency, is where a male will lack male hormones and have a more female appearance [3]. Many believe that gender categories are limited to physical appearance; however, between .01% to 1.7% of infants are born intersex with ambiguous genitalia [4]. Whether it is due to hormonal disorders or being born intersex, many people do not fit within the dual categorization that is implied within bathroom bill legislations.

“Through differences in hormones, chromosomal sex usually leads to corresponding body appearance. However, there are several cases where the chromosomal sex of an individual does not match their hormone production due to various naturally occurring disorders.”

“Researchers have observed that brain structures in male to female transgender individuals can be significantly different from a typical male and more comparable to female counterparts, suggesting that brain structures may match their identity instead of their assigned sex.”

Early in life, brain formation is influenced by surging hormones. Depending on whether the hormone estradiol is let into the brain early on, a brain becomes “masculinized” or “feminized” [5, 6]. Differences in brain structure are not functionally understood, but some differences do exist between the “feminized” and the “masculinized” brain. The relay center for motor systems, a structure called the basal ganglia stria terminalis, is larger in females than in males. Additionally, estrogen is associated with the brain’s communication between hemispheres across the corpus callosum to process language, whereas testosterone is associated with language processing on one side of the brain [7]. Researchers have observed that brain structures in male to female transgender individuals can be significantly different from a typical male and more comparable to female counterparts, suggesting that brain structures may match their identity instead of their assigned sex [5, 8]. In fact, Dick Swaab, an expert in sex hormones and neurobiology, has found through various brain studies that gender identity is likely formed in the womb when the first surge of hormones occurs. He also found little evidence supporting the impact of social environment on gender identity [5, 9] . Concomitantly, this presents evidence that there is a biological response to gender identity. In fact, many believe that once gender identity is established, it is irreversible, confirming that gender identity should be considered over assigned sex, especially in proposed legislations regarding transgender individuals [9, 10].

From an early age, children have been shown to have different ways of playing that arise from hormone levels, categorized as male or female typical [11]. Females more traditionally play with dolls and draw, while males typically participate in rough and tumble play, and construct with blocks. However, females with more androgens, or male hormones, partake in male typical play, suggesting that hormones also have an affect on the behavior of an individual. Individually, one may fall anywhere on a spectrum of male or female hormones within their body, again lessening support for a strict, dual categorization of female and male [11].

Complex behaviors such as math skills, verbal skills, motor skills, and physical abilities, are less strongly linked to hormones than play [8]; socialization and hormones both play a role in the different abilities found between genders. Men tend to perform better in spatial tasks and target motor skills [8, 12]. Women generally excel in fine motor skills, verbal abilities, and perceptual speed. Social environment affects the way children develop, the entities they choose to like, and the activities and subjects in school they seek out [13]. Parents often start socializing their children based on gendered stereotypes, often about type of play, sports, and math and writing performance [14]. Teachers continue this socialization in the classroom where boys are seen as more competent and rambunctious, and girls are expected to be quiet and polite. This leads to teachers calling on male students more often, and giving them more attention in the classroom [9]. Socialization plays a large role in one’s gender identity, and is another element that complicates a dual categorization of gender.

Dividing gender into two rigid categories does not fully encompass every individual, whether that be because they have a hormonal disorder, they were born intersex, or their assigned sex does not match their identified sex. When making legislation, gender should be treated as a dual concept, and must be representative of all individuals, not just those that fit into social stereotypes. Legislators must take care to understand the research before making decisions that can have wide ranging effects on the public opinions and transgender individuals.

“A time-consuming activity that every individual across the globe participates in is sleep. If an individual lived 80 years, approximately 27 years will have been spent sleeping, assuming eight hours of sleep each night.”

REFERENCES

  1. Kralik, J. (2017, July 28). “Bathroom Bill” Legislative Tracking.
  2. Bianco, Marcie (April 2, 2016). “Statistics Show Exactly How Many Times Trans People Have Attacked You in Bathrooms”
  3. Beatty, W. W. (1979). Gonadal hormones and sex differences in nonreproductive behaviors in rodents: Organizational and activational influences. Hormones and Behavior, 12(2), 112-163. doi:10.1016/0018-506x(79)90017-5
  4. Blackless, M., Charuvastra, A., Derryck, A., Fausto-Sterling, A., Lauzanne, K. and Lee, E. (2000), How sexually dimorphic are we? Review and synthesis. Am. J. Hum. Biol., 12: 151–166. doi:10.1002/(SICI)1520-6300(200003/04)12:2<151::AID-AJHB1>3.0.CO;2-F
  5. Bao, A., & Swaab, D. F. (2011). Sexual differentiation of the human brain: Relation to gender identity, sexual orientation and neuropsychiatric disorders. Frontiers in Neuroendocrinology, 32(2), 214-226. doi:10.1016/j.yfrne.2011.02.007
  6. Bakker, J., Mees, C. D., Douhard, Q., Balthazart, J., Gabant, P., Szpirer, J., & Szpirer, C. (2006). Alpha-fetoprotein protects the developing female mouse brain from masculinization and defeminization by estrogens. Nature Neuroscience, 9(2), 220-226. doi:10.1038/nn1624
  7. Luders, E., Thompson, P. M., & Toga, A. W. (2010). The Development of the Corpus Callosum in the Healthy Human Brain. Journal of Neuroscience, 30(33), 10985-10990. doi:10.1523/jneurosci.5122-09.2010
  8. Kimura, D. (2003). Sex differences in the brain. Scientific American-American Edition-, 287, 32-37.
  9. Teacher Bias. (n.d.). The SAGE Encyclopedia of Psychology and Gender.
  10. Bao, A., & Swaab, D. F. (2010). Sex Differences in the Brain, Behavior, and Neuropsychiatric Disorders. The Neuroscientist, 16(5), 550-565. doi:10.1177/107385841037700
  11. Henderson, B. A. and Berenbaum, S. A. (1997), Sex-typed play in opposite-sex twins. Dev. Psychobiol., 31: 115–123. doi:10.1002/(SICI)1098-2302(199709)31:2<115::AID-DEV4>3.0.CO;2-N
  12. Blum, D. (1997). Sex on the brain: The biological differences between men and women. Penguin.
  13. McGurk, H. (1993). Childhood social development: contemporary perspectives. Hove: Lawrence Erlbaum.
  14. Eccles, J. S., Jacobs, J. E., & Harold, R. D. (1990). Gender Role Stereotypes, Expectancy Effects, and Parents Socialization of Gender Differences. Journal of Social Issues, 46(2), 183-201

 

This piece was featured in Volume III Issue I of JUST.

2017-12-12T23:56:35+00:00 December 14th, 2017|