Development of Diverse Sexual Orientations in Humans - Report Example

Deep studies of the development of diverse sexual orientations in humans begets only new versions, rather than presents a universal explanation Introduction For a long time people try to understand what factors influence on diverse sexual orientations. Some of them keep simple interest on this issue while others intentionally ignore the fact of homosexuality, sometimes displaying heterosexualism or individual homophobia. While all these people have some thoughts on this issue, hardly somebody of them can clearly operate by well known and scientifically proved arguments that are perceived as a common truth. Biologists, sociologists, psychologists and other professionals do investigate the issue of different sexual orientation among humans, conducting more and more studies and researches in attempts of finding the most reliable answer. Deep studies of the development of diverse sexual orientations in humans begets only new versions, rather than presents a universal explanation There exist many different scientific studies and methodologies aimed at understanding the factors, influencing human sexual orientation. These factors can be differentiated by two or even three categories, including: social factors, biological factors or “symbioses” of both social and biological factors. Mustanski et al., (2002) in their research review mainly the influence of biological factors on sexual orientation and concludes that biological influences do have impact on human sexual behavior to some extent. While exploring biological influences on sexual orientation, empirical researchers are used to apply two approaches: impact of hormones on development of sexual orientation, and behavioral genetics. The first approach is based on the neurohormonal theory and strives to evaluate the role of used hormones in forming a fetus and genitals of infant. Results of the research show the relationship between prenatal androgen activity and development of sexual orientation of both men and women (Mustanski et.al, 2002: 97). In order to obtain more evidence on this issue, I have referred to another external source which is based on the primary research and provides certain conclusions at this point. Ellis and Hellberg (2005) have undertaken a study in order to understand whether prenatal exposure to therapeutic drugs impact on the development of human sexual orientation. This research was focused on those drugs which were more likely to affect the hormone level. This link was aslo supported previously by Mustanki et al. (2002) because misbalance of sex hormones levels lead to sexual differentiation of the fetal brain. To be more precise, Mustanski et al. (2002: 97) mentions “that prenatal hormones hard wire sexual orientation into fetal brains”. For studying the impact of the use of drugs during gestation, researchers have taken a sample of 5102 mothers and collected reports of mothers and their offspring regarding their sexual orientation. According to the results of survey, less than 15% of pregnant women have taken at least one drug or class of drugs, however there was found little evidence on prenatal exposure to drugs among male offspring (Ellis and Hellberg, 2005). While this theory failed to work in relation to male scion, there was evidence that some drugs did have some impact on sexual orientation among female offspring. These were two types of drugs, which consisted of synthetic thyroid medications and amphetamine-based diet pills (Ellis and Hellberg, 2005). This tendency might be explained by the fact that during the first three months of being pregnant mothers of lesbian offspring did consume high doses of drugs prescribed. From this study there have made a conclusion that prescription drugs such as mentioned above have influence on the immune system of developing female fetuses. Immune system may impact on the processes of feminization of the brain among males, and masculinization of the brain among females. These “reverse” reactions of the brain might result in different sexual orientations of offspring. According to the neurohormonal hypothesis, homosexuality of men depends on low prenatal androgen action, while homosexuality of women depends on high prenatal androgen action (Mustanski et.al, 2002). Thus, Ellis and Hellberg (2005) by their research supported the neurohormonal theory where immunological factors also should be taken into consideration while researching evolution of sexual orientation. The second approach known as behavioral genetics is based on identifying the source and evaluating the scope of genetic impacts on sexual orientation. Thus, for example, Mustanki et al. 2002 provides some evidence that such factors as maternal stress, smoking, etc. also might have its impact on development of fetus sexual orientation. In the research, Mustanski et al., 2002 reviews many different versions that are scientifically tested but have serious limitations. For example, some scientists applied hormonal manipulations with animals, not taking into account human data; other scientists did not include lesbian women while testing “the role of brain regions in sexual behavior” (Mustanski et.al, 2002: 100). Even though because of such limitations not all studies reflect objective reality of the case, it has been suggested that non-shared environmental factors as well as genetic factors influence on the development of sexual orientation. However, while choosing and using only single measure for understanding an individual’s sexual identity is considered to provide not enough “the true answer” (Mustanski et.al, 2002: 125). Complex analysis of different factors and influences also plays a critical role in evaluating the degree of impact of these factors on development of sexual orientation between women and men, because there is some evidence of different magnitude of the agreement between factors in relation to both sexes (Mustanski et.al, 2002: 125). Another evidence based theory refers to the relationship between sex orientation and handedness. While lesbian women demonstrated a sex-atypical pattern for homosexual subject, showing increased left-handedness in comparison with the heterosexual women, gay men did not (Mustanski et.al, 2002: 100). Another evidence, based on the theory about the role of the third interstitial nuclei of the anterior hypothalamic (INAH-3, specific brain region) in sexual orientation, shows that cell volume in INAH-3 is significantly larger among heterosexual men than among gay men and heterosexual women (Mustanski et.al, 2002: 103). However, there is no evidence in relation of this theory to lesbian women. One more evidence on the difference in the development of sexual orientation for males and females relates to click-evoked otoacoustic emissions (CEOAEs). CEOAEs are “waveforms, emitted by the inner ear to brief sounds” women (Mustanski et.al, 2002: 104). According to the result of research of 237 subjects, women have demonstrated an obvious effect on sexual orientation, where heterosexual women emitted more female typical CEOAEs than bisexual and lesbian women did; men have shown no difference in emitted CEOAEs. Another one research has been held with a goal to explore the genetic nature of sexual orientation in twin studies. The results of the studies demonstrated the influence of genes on sexual orientation. Evidence based conclusion was made that “genes influence sexual orientation more strongly in males than females” (Mustanski et.al, 2002: 113), 161 vs. 147 pairs. There is another one evidence based theory based on the fraternal birth-order effect on homosexual men. Even though this theory doesn’t imply potential influence on women, it clearly demonstrates the evidence of difference in the development of sexual orientation for males and females. According to statistical analysis, about 15% of men are more likely to become homosexual due to fraternal birth-order effect (Mustanski et.al, 2002: 119). Thus, we see that there are functional and structural brain differences that impact on the development of human sexual orientation. Despite all above mentioned theories on the differences in the development of sexual orientation for males and females, there is still a lack of evidence in this area, partially because often females are not involved in research, partially because of developing not enough objective measures of female sexual orientation, and finally because of comparatively limited research on biological basis of sexual orientation in women (Mustanski et.al, 2002). Conclusion Despite modern technologies and tremendous scientific break, scientists do continue to face a challenge of finding a proper scientific explanation accounting for the development of diverse sexual orientations in humans. Despite the variety of different versions, presented above and supported by scientific researches, no universal explanation on this topic has been derived. While for some versions more sophisticated technologies are required, for other versions there is an obvious lack of arguments. Thus, for example, the Ellis and Hellberg tried to prove the relationship between use of therapeutical drugs by women during pregnancy and sexual orientation of their female offsprings. Partially they did, supporting the neurohormonal theory. However, this argument seems to have not enough weight of itself, because long ago before, there were not even such drugs but homosexuals existed. Mustanski et.al also reviews a broad variety of different factors, trying even to identify the differences between males and females. However, for making certain conclusion he often claims that more research is required. Biblography: Ellis, Lee and Hellberg Jill. “Fetal exposure to prescription drugs and adult sexual orientation”. Personality and Individual differences 38(2005). Mustanski, B., Chivers, M., and Bailey J.M. “A critical review of recent biological research on human sexual orientation”. Annual review of Sex Research 13 (2002): 89-140. Read More