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Choosing to have sexual relationship with the same sex is known as homosexuality, the opposite sex (heterosexuality), or both sexes are known as bisexuality. All of these are different types of sexual orientations. In the past there were some people who believed that heterosexuality was what God had said to be normal and good while anything other than that would be the work of the devil or a sin against God. There have been many theories that account for the development of diverse sexual orientations in humans.
One of the most influential ones is known as the neurohormonal theory. The neurohormonal theory looks at the prenatal androgen levels, with heterosexual men on the higher end, heterosexual women on the lower end, and homosexual men and women at intermediate levels (Ellis, Ames 1987: 248). With all the studies that have been conducted, it seems that the role of the prenatal sex hormones androgen may give us the different types of sexual orientations. Biological factors seem to outweigh environmental factors when it comes to contributing to sexual orientations.
Not saying that environmental factors do not contribute to developing sexual orientations, because that still remains uncertain at the moment. Biologists would strongly disagree while psychologists would agree that environmental factors influence sexual orientation. If a person growing up is sexually abused or neglected, or lived in a dominantly paternal or maternal environment, Psychologists would argue that these types of factors can contribute to shaping a person’s sexual identity. Joan Roughgarden would argue that a person’s sexual orientation is like a person’s accent.
It’s developed at a very early age and most people can’t change it while others can. (Roughgarden 2009: 256) ??Though the accents are not genetic, they are thick most of the times because of the secluded surrounding environment that people live in for long extended periods of times that helps keep it intact. An example of this would be that older generation people who are let’s say born and raised in England have a thick English accent and most of the times they can’t stray away from their accents because all their lives they were exposed to it.
While other younger people can change their accents because they might be possibly exposed to more diverse cultures or live abroad where their mother tongue is a secondary language, Roughgarden compares that with sexuality saying that some people can sway into heterosexuality or homosexuality and can be open when it comes to their orientations. (Roughgarden 2009: 257) ?? After having read Mustanskis’ article, A Critical Review of Recent Biological Research on Human Sexual Orientation, the levels of androgen or the lack of the hormone has some effect on an individual’s sexual orientation.
Androgen is a hormone that develops male characteristics like penis and body hair. Females also have androgen, but in low amount. Testosterone is a type of androgen and it influences the sperm-cell formation. (Ellis, Ames 1987: 233) In two studies conducted by Pearcey, Singh and others in 1999, two types of lesbian women, either butch or femme were looked at to determine which group had a higher level of testosterone. In both studies they found significant differences in salivary testosterone levels among lesbian women (Mustanksi, Chivers, Bailey 2002: 92).
Since the butch lesbian women are consider to be more masculine, they may have a higher amount of testosterone levels in their bodies compared to the more femme lesbians. Prenatal sex hormones can also influence sexual orientation, and these influences may be seen later on in adult life. There are certain hormonal problems that can occur in a person body where they either produce too much androgen or not enough. And this ability to produce too much or not enough androgen may have an effect on sexual orientation.
In congenital adrenal hyperplasia syndrome (CAH), the body cannot produce the hormones cortisol and aldosterone. Without these hormones the body produces more androgen which is a type of male sex hormones, and this causes male characteristics to appear (Mustanksi, Chivers, Bailey 2002: 95). For a female fetus this can produce many problems such as genital masculinization. A study showed that despite “surgical correction of the genitals at birth and rearing as females, longitudinal studies have found that the behavior patterns of persons with CAH tend to be unusually masculine for females” (Ellis, Ames 1987: 246).
The study found that these women were more likely to play competitive sports, and are less likely to prefer playing with dolls and dressing in feminine clothing (Ellis, Ames 1987: 246). The study also reported fewer fantasies about romance and marriage. Their mannerisms and gestures were also described as more male like than those of most females (Ellis, Ames 1987: 246). This shows the effect of the hormone androgen on sexual orientation. The increased level of androgen look like it affected or altered the sex role of the women.
Usually when you think of a woman you think of someone who dresses more feminine who is less likely to play competitive sports, but it is the opposite in the study mentioned above. There are also some people who have androgen insensitivity syndrome (AIS). AIS affect males, and they are resistant to the male hormone androgen. Persons with this syndrome “develop testes that produce normal or above normal male quantities of testosterone, but they lack androgen receptor sites to bind to the hormone in a normal way” (Ellis, Ames 1987: 246).
This leads a child to look as a female because they seem to have female characteristics, so then they are raised as females from birth. A study showed that “sexual attraction to men were reported by 100% of the women during adolescence, and by 93% during adulthood” (Mustanksi, Chivers, Bailey 2002: 96). This shows that not having the prenatal androgen hormone caused an attraction to men. Pharmaceutical drugs can also have an effect on sexual orientation.
There is a study that shows evidence of the effects of excess androgens in females from diethylstilbestrol (DES) which is a nonsteroidal estrogen that has the same masculinizing effects, but not the same magnitude as you see in CAH (Mustanksi, Chivers, Bailey 2002: 96-97). In these study women who were given DES during pregnancy reported that they had an increase in homosexual fantasies (Mustanksi, Chivers, Bailey 2002: 97). This shows us further proof of the effects of androgen in determining sexual orientation.
Many homosexuals do not have problems associated with CAH or AIS, so there has to be other explanations that link sexual orientation and hormone levels. Prenatal stress may have some effect on sexual orientation. There were two studies that showed this effect. In the first study, “Dorner found that, among males born in Germany between 1934 and 1953, an unusually high proportion of homosexuals were born during and immediately after the Second World War (i. e. , between 1941 and 1946)” (Ellis, Ames 1987: 249). This was a very stressful time for most German citizens, and perhaps especially so for pregnant women (Ellis, Ames 1987: 249).
In another study done by Ellis, she surveyed a small group of mothers about stress during pregnancy and found a trend that showed an increase in stress during the second trimester for mothers of gay offspring (Mustanksi, Chivers, Bailey 2002: 98). According to a news article on University of Texas, it stated that high level of stress causes a release of cortisol which may play a role in blocking testosterone (Ellis, Ames 1987: 255). Low amount of testosterone levels may have an effect on sexual orientation because a male may have some female features like increased breast size.
There have not been many studies that have been done with stress and its effects on sexual orientation. So this leads us to look at functional cerebral asymmetry (FCA) which refers to how the hemispheres of the brain are divided up and what part controls language and spatial abilities (Mustanksi, Chivers, Bailey 2002: 99). Handedness is part of FCA and studies show that “developmental instability (DI) may better account for the observation that elevated rates of non-right-handedness have been reported in both gays and lesbians” (Miller, Hoffmann, Mustanksi 2007).
As mention in previous paragraphs, the neurohormonal theory says that male homosexuality relies on low prenatal androgen levels while female homosexuality relies on high prenatal androgen levels. In the same Mustanksi and Hoffmann article, the neurohormonal theory predicts higher rates of non-right-handedness only in lesbian women because non-right-handedness is a sexually dimorphic trait seen more often in men (Miller, Hoffmann, Mustanksi 2007). Handedness can also show its relation to prenatal hormone exposure. Perelle and Ehrman found men to be left handed slightly more often than women (Miller, Hoffmann, Mustanksi 2007).
You can also find increased left-handedness in populations where prenatal hormone levels of androgen were increased, and this is something you can see in congenital adrenal hyperplasia. You also see it in women born to mothers who took diethylstilbestrol, a non-steroidal synthetic estrogen (Miller, Hoffmann, Mustanksi 2007). Some studies looked at the role of specific brain areas and its connection to sexual behavior. Researchers looked at a region of the brain which is called the third interstitial nuclei of the anterior hypothalamic (INAH-3). They were trying to look at if this region has any effect of sexual orientation.
They found that males had a larger INAH-3 region than women, and when looking at homosexuals, they found that there were almost same amount of cell volume in INAH-3 between heterosexual women and gay men (Mustanksi, Chivers, Bailey 2002: 102-103). Both heterosexual women and gay men had a very small cell volume in that region compared to heterosexual men (Mustanksi, Chivers, Bailey 2002: 102-103). This may be due to the different levels of prenatal androgen that is in their systems. Homosexual men and heterosexual women may have a low amount of testosterone, which is a type of androgen, in their system.
Some of the researchers tried to see the role of hormones in CEOAEs. Click-evoked otoacoustic emissions (CEOAEs) are sound waves that are emitted by the inner ear (Mustanksi, Chivers, Bailey 2002: 104). In a study by McFadden and Pasanen, they found that lesbian and bisexual women emitted lower (more male typical) CEOAEs than heterosexual women (Mustanksi, Chivers, Bailey 2002: 105). Other researchers looked at the brain waves in response to click stimuli, called auditory evoked potentials (AEPs), and found similar results in women that you would expect in males (Mustanksi, Chivers, Bailey 2002: 105).
When it came to these studies for men, the results were inconclusive. These results may mean that the prenatal hormone androgen has some effect on both sexual orientation and the auditory system. There has been a lot of research done on the anthropometric characteristics that are related to sexual orientation. One of the characteristics is finger length. Researchers looked at finger length ratio of the index finger (2D) and ring finger (4D) between male and females, and found that the ratio is same in women, but usually smaller in men.
Smaller 2D:4D ratio meant that there was a greater level of prenatal androgen exposure (Mustanksi, Chivers, Bailey 2002: 105). The 2D:4D ratio was smaller than the control group in children with congenital adrenal hyperplasia (Mustanksi, Chivers, Bailey 2002: 106). Data also showed that the ratio was smaller in lesbian women (more masculine) compared to heterosexual women, and not very different from heterosexual men (Mustanksi, Chivers, Bailey 2002: 106). This again shows the effects of androgen as the ratio of lesbian women and children with CAH have the same results as men.
Evolution naturally favors heterosexuality because it helps pass genes to the individual’s offspring. But the question is how has homosexuality still maintained in history? Some say that homosexuality is like a side product of evolution and in general sexual orientation (Roughgarden 2009: 144). In primates and other animals’ same sex activities do not really interrupt with reproduction because females still tend to have a large amount of offspring who then later on grow up and engage in homosexual activities, but still reproduce their own offspring.
Joan Roughgarden stated that the “more complicated the social system was for animals the more likely homosexuality would exist…” (Roughgarden 2009: 144). Some scientists say that over time homosexuality has gained more of a distinction in some species such as humans and primates, while in others have not been majorly present. This make a you wonder whether or not hormones have an effect on sexual orientations. There have been conflicting reports on what causes the development of different sexual orientation in humans.
In my opinion I believe that both environmental and biological factors influence sexual orientation. I think that while hormones like androgen have a great deal of influence in one’s identity, I believe the surrounding environment then come into play and helps determine a person’s true sexual orientation. One detail that solidifies this assumption is that a lot of people take more time in their lives to discover their sexuality. References 1) Miller, Hoffmann, and Brian S. Mustanksi. “Fluctuating Asymmetry and Sexual Orientation in Men and Women. Archives of Sexual Behavior (2007). Accessed November 23, 2011. doi: 10. 1007/s10508-007-9256-2 2) Lee Ellis and Ashley M. Ames. “Neurohormonal Functioning and Sexual Orientation: A Theory of Homosexuality-Heterosexuality. ” American Psychological Association 101 (1987): 233-258. Accessed November 23, 2011. doi: 0033-2909/S7/S00. 75 3) Mustanksi, Chivers, and J. M. Bailey. “A Critical Review of Recent Biological Research on Human Sexual Orientation. ” Annual Review of Sex Research 13 (2002): 89-140. Accessed November 23, 2011. 4)