Biological Foundation for Homosexuality - Term Paper Example

Abstract

Homosexuality is a type of sexual orientation divided into gay and lesbianism. Gay refers to a male who feels emotional and sexual attraction to another man. On the other hand, a lesbian is a female who develops an emotional or sexual attraction towards other women. The opposite of homosexuality is heterosexuality, which involves developing a sexual attraction towards members of opposite sex. This paper discusses the evidence that supports a biological foundation for homosexuality. Biological determinants identified in this article are genetics, hormones and brain structure. From studies conducted by several researchers, homosexuals inherit most of their traits from parents. Similarly, twin studies, epigenetics, and adopted sibling studies show that genes contribute to homosexual orientation. A particular gene identified to cause homosexuality is Xq28. Finally, the paper shows that brain parts and exposure of the fetus to hormones such as androgens lead to homosexual behaviors.

Evidence that Supports Biological Foundation for Homosexuality

Introduction

Homosexuality is one of the debated issues globally. For example, in the United States, President Barack Obama, and human rights activists are on the frontline fighting for the equal rights of homosexuals. On the other hand, governments in most developing countries, especially in Africa, condemn homosexuality and those found practicing it are liable to imprisonment or hefty fines. Many people believe that homosexuality is a western culture determined by social constructs, socioeconomic status and level of education. However, scientists have come up with several theories supporting that biological factors determine homosexuality. In a study conducted by Dr. Eric Vilain, a professor of human genetics at University of California Los Angeles, biological factors determine homosexuality include genetics, hormones and brain structure. Several researchers report similar findings from their intensive studies. In essence, there is enough evidence to support that biological factors such as genetics, brain structure, and hormones influence homosexual behaviors.

Genetic Factors

First, molecular genetic studies conducted by several scientists identify a gene-linked homosexuality directly. According to Lee (2010), the gene identified as “gay gene”, shows that homosexuals have homosexual relatives in their family lineage. Studies show that a region on the X chromosome contains the gene known as Xq28 (Lee, 2010). In fact, gay brothers share more than 50% of alleles located in the Xq28 region. During the annual meeting of American Association for the Advancement of Science in Chicago, scientists revealed that among 409 gay men, two chromosomes influenced sexual orientation. Apparently, men inherit Xq28 region from their mothers. Likewise, chromosome 8 has another inheritable region, which determines sexual orientation. Therefore, many scientists believe that more than one gene influences sexual orientation. Lee (2010) indicates that genetic analysis shows that Xq28 gene has three regions, which altogether contain 8mb information. The gene belongs to Melanoma-associated antigen family (MAGE) which contains 12 other genes. Many studies support that Xq28 region influences homosexuality. For example, Dean Hamer identified the presence of the gene in 83% of sibling pairs. Besides, Stella Hu conducted similar studies and found out that many homosexual siblings have Xq28 gene at the same location. From the studies carried out by Dean Hamer and Stella Hu, only a small percentage of same-sex siblings lacked the gene on the X chromosomes. Lee (2010) states that since a large percentage of the findings reveal the presence of the same gene on chromosomes of the study population, then, it is undisputable that Xq28 is responsible for homosexual behaviors.

Second, twin studies reveal that genes influence homosexual traits (Balthazart, 2011). Evidently, geneticists use monozygotic and dizygotic twin studies to distinguish genetic and environmental factors that influence phenotypic behaviors. It is apparent that homosexual twins reared together get exposure to same environments. Thus, genetics helps to identify the exact cause of homosexual behaviors, which is absent in non- twin siblings. Kallmann, a geneticist, was the first to conduct twin study on homosexual behaviors among males. Despite defects in his methodology such as concordance and mentally ill gays, Kallmann found out that both monozygotic and dizygotic twins share same genes that influence homosexuality. Several researchers have conducted genetic studies and identified that lesbian and gay characteristics result from genetic factors. For instance, Bailey, a researcher, conducted one of the largest twin studies on homosexuality. His findings related ton results from similar studies that twins share some genes that influence homosexuality. Therefore, adequate evidence leads to a conclusion that genes have a great role in influencing homosexuality.

Third, adoption studies reveal that homosexuality relates to genes (Balthazart, 2011). These studies involve adoptive siblings growing in a similar environment with homosexuals. Unlike related siblings who share genes, foster siblings show differences in expression of homosexual behaviors. Specifically, adopted siblings do not share any genes related to homosexuality. On the other hand, siblings from same biological parents have specific genes for homosexuality. Therefore, due to genetic differences, it is likely that biological siblings will have related homosexual behaviors. On the other hand, when environmental factors are constant, adoptive siblings do not express same gay patterns. In essence, biological siblings inherit gay genes from their parents. On the other hand, adoptive siblings may or may not inherit homosexual genes.

Finally, epigenetic studies show that genes influences expression of homosexual traits in men and women (Balthazart, 2011). In fact, there is substantial evidence to show that some environmental factors affect genes, which in turn regulate development of homosexual or heterosexual orientation. Typically, women possess double X chromosomes; however, one is inactive. Therefore, the inactive chromosome in the mother influences development of homosexual traits in her sons. In fact, scientists argue that turning on and off genes on the X chromosome determine the development of homosexuality. Apparently, environmental factors activate or inactivate genes. Further evidence shows that mother inherits epi-marks on their X chromosomes and passes them to their offspring. Resultantly, activation of the epi – marks by environmental factors leads to the onset of sexual attraction towards the same sex in the adulthood. Notably, substances that influence activation of the genes or modification of the epi-marks include medicines, plasticizers, and toxic compounds.

Hormones

Hormones influence the development of sexual orientation traits. Specifically, homosexuality results from male and female hormones such as testosterone and estrogen. Scientific evidence shows that sexual orientation results from embryonic sex steroid. According to Balthazart (2011), sexual orientation does not result from activation of sex hormones in adulthood. Instead, homosexual behaviors begin to occur at early stages of fetal development. Specifically, variations in embryonic exposure to sex hormones determine the sexual orientation that will develop in adulthood. For example, Balthazart (2011) claims that exposing the fetus to high testosterone concentration during the early development period influences male-typical orientation characterized by a strong attraction to women. In other words, exposing females to high testosterone during fetal development increases their chances of becoming lesbians in their adulthood. Equally, important, exposing the fetus to low concentration of testosterone causes female – typical orientation characterized by a strong attraction to men. To elaborate further, exposing males to low testosterone leads to development of gay behaviors when they grow into adults.

Several studies provide evidence to show the relationship between hormones and homosexuality. Notably, all researchers indicate that hormonal balances determine the hormones exposed to fetuses in the womb. According to Balthazart (2011), finger digit length ratio predicts the exposure to hormones such as testosterone, estrogen, and luteinizing hormone. For example, women’s index finger (2D) and fourth digit (4D) have the same length. Conversely, men have a shorter index finger that the fourth. Apparently, a higher 2D:4D ratio in females occurs among the two-year-olds. Several studies hypothesize that exposing prenatal males to androgen hormones during the fetal age determines the sex differences based on the 2D:4D ratio. Unlike men, the 2D:4D ratio in homosexual women is small. These findings depend on the high exposure of women to androgen hormones in the womb; hence, they develop a homosexual orientation. The proxy figure is the best determinant of homosexual orientation in females because it is difficult to measure the hormone levels. Further, the same study revealed that males with many older brothers are likely to become homosexuals because of increased exposure ton androgen in the uterus. In fact, men with more men siblings have a lower 2D:4D ratio. Accordingly, it is possible to determine the influence of hormones on sexual orientation using the index finger to the fourth finger (2D:4D) ratio (Balthazart, 2011).

Furthermore, studies on congenital adrenal hyperplasia (CAH), a hormonal imbalance condition resulting from defective in 21-hydroxylase enzyme, shows that hormones influence the development of homosexual orientation. Balthazart (2011) states that CAH leads to the production of increased hormones during fetal development. From the findings, an increase in production of androgens has a minimal impact on sexual orientation in males. On the other hand, female fetuses developing in regions with high concentration of androgens have large external genitalia. When exposed to dexamethasone treatment while still in the womb, the androgen imbalance reduces leading to development of female traits both phenotypically and genetically (Balthazart, 2011). Therefore, the ability of dexamethasone to prevent development of homosexual traits in women proves that androgen hormones influence homosexual orientation in prenatal.

Brain Structures

The study of different brain structures in homosexuals and heterosexuals demonstrates how brain influences development if homosexual orientation. To begin with, gay males have a larger suprachiasmatic nucleus than in heterosexuals (Bao and Swaab, 2011). Suprachiasmatic nucleus is located in the hypothalamus and regulates the circadian rhythms. Although there is inadequate information on the relationship between this region and sexual orientation, several scientists hypothesize that men with a large suprachiasmatic nucleus tend to express homosexual behaviors. Next, Bao and Swaab (2011) note that anterior commissure determines homosexual orientation in men. Apparently, heterosexual subjects have a smaller anterior commissure. Conversely, gays have a large anterior commissure. Further, the findings by researchers at the University of California show that homosexual men had a larger Interstitial Nucleus of the Anterior Hypothalamus (INAH) than in heterosexuals (Balthazart, 2012). In the same region, homosexual men had a high cell density characterized by numerous neurons. By contrast, heterosexual males had a low cell density in the interstitial nucleus of a few neurons.

Apparently, the brain is the center of sexual attraction in human beings. Therefore, the anatomy of the brain determines sexual orientation between men and women. Evidently, the pre-optic region of hypothalamus expresses dimorphism in both males and females (Bao and Swaab, 2011). Further, the INAH region varied in size between men and women. Since INAH is directly related to sexual dimorphism, many scientists have hypothesized that the area has several differences in heterosexuals and homosexuals.

In another study by Savic and Lindstrom (2008), findings show that homosexuals and heterosexuals have significant differences in the cerebral. From brain scan images, homosexuals have similar structure and functions that differ from heterosexuals. Indeed, the study demonstrates that lesbians and straight men share same structures whereas straight women and gays have similar neural connectivity. Further research work reveals that gray matter determines the sexuality of both men and women. For example, male-to-male transsexuals have more gray matter than heterosexuals do (Savic and Lindstrom, 2008). In a similar fashion, lesbians have high gray matter than straight females in the putamen region.

Then, neurological differences help in shaping behaviors among different groups of people. For this reason, neurological differences determine the sexual preferences in homosexuals and heterosexuals. Indeed, homosexual and heterosexual women respond to odors differently. For instance, odors emitted by 4, 16- androstadien-3-one (AND), a testosterone component found in the sweat of men estra-1, 3, 5 (10), 16-tetraen-3-ol (EST), an estrogen substance present in females (Balthazart, 2012). Upon inhalation of AND chemical, straight women and homosexual men express similar brain activation in the hypothalamus region. Contrastingly, exposing straight women to EST had a high activity in the olfactory region. Scientifically, olfactory region processes smell whereas the hypothalamus processes sexual signals. Therefore, Balthazart (2012) concludes that homosexual men respond actively and express attraction to other men who produce the AND substance.

Conclusion

The impact of biology on the development of homosexual orientation is one of the topics debated by many worldwide. Indeed, several scientists have come up with enough evidence to support their claims that biological factors influence homosexual behaviors in both men and women. To start with, genes play a central in the development of gay and lesbian traits. Specifically, scientists have identified a gay gene known as Xq28, which leads to a high sexual attraction towards members of same sex. Still, on the genetic influence, epigenetics, twin studies and adoption studies show that homosexuality depends majorly on genetic inheritance. Next, hormones contribute significantly to homosexual orientation. Specifically, exposing the fetus to high androgen concentration can lead to the development of homosexual traits. Lastly, brain structures determine the differences between heterosexuals and homosexuals. For example, gay men have larger brain regions such as gray matter, INAH, and anterior commissure. In essence, future studies should focus on determining how regulation of the identified biological factors can help to reduce the increasing number of homosexuals.