Homosexuality is a term that invokes a response that is colored by various opinions, be it social, political or personal. Sexual orientation refers to as the sexual affinity for men or women or both. Normally, People who are sexually attracted to members of the same sex are called homosexuals. Being an uncommon trait, homosexuality is not well-received by society. However, statistically, homosexuality is a surprisingly common trait in human populations (e.g. a prevalence of about 8% in both sexes was reported in a large and systematic sample in Australia (1)). To some extent some homosexual people in Australia have been demonstrating saying that they should be given their rights to acts as homosexuals.
When analyzing homosexual origin it can be said that an individual’s attitude towards sexual orientation influences one’s notion of the causes of sexual orientation. Therefore, determining the cause behind homosexual behavior plays a crucial role in changing the social and political perceptions of ‘gay’, ‘lesbian’ or ‘bisexual’ individuals. People have tried to come up with scientific explanations pin pointing the cause of this anomaly in sexual development but with limited success. In 1993, a team that was led by geneticist Dean Hamer of the National Cancer Institute reported in Science that one or more genes for homosexuality (“gay genes”) had to reside on Xq28, a subtelomeric region of the long arm of the X chromosome (2). The discovery generated ripples worldwide, but some teams were unable to replicate the findings (3) and the actual genes were not found by a team that supported Hamer’s identification of Xq28 in a sample size 10 times larger than his. Homosexual orientation not being a simple Mendelian trait, it is safe to assume that simple gene sequences cannot totally account for homosexuality.
Twin studies also suggested that the identical twin of a gay man, despite having the same genome, only has a 20% to 50% probability of being gay himself. Other independent studies have revealed the influence of neuroanatomical differences and prenatal androgens in determining partner preference. Three brain regions have been implicated in influencing sexual orientation in males. The anterior hypothalamus anterior plays a role in the regulation of male-typical sexual behavior. Volumes of Four cell groups in this region [interstitial nuclei of the anterior hypothalamus (INAH) 1, 2, 3, and 4] from three distinct groups; heterosexual men and women, and homosexual men, were measured in postmortem tissues. While there were no differences between the groups in the volumes of INAH 1, 2, or 4; INAH 3 was found to be smaller in gay men and more similar in size to heterosexual females (4). The arginine vasopressin neuronal population of the suprachiasmatic nucleus and the anterior commissure in gay men (5) is larger than those in heterosexual males and females. However, the findings were not fully backed up because there was some information that showed that genetic information cannot determine or be the cause of homosexual.
In addition, Epigenetics is a relatively new sub-discipline of genetics that is gaining an increasingly important role in evolution and heritability. Changes in chromatin structure that alter the transcription rates of genes, such as nucleosome repositioning, DNA methylation, and/or modification of histone tails, but (no changes in DNA sequence) are called epi-marks. A parent’s epi-marks sometimes are transferred across generations and determine the phenotypes of offspring (8). Since the genes responsible for androgen sensitivity reside on autosomes, it is conceivable that sex chromosome epi-marks can regulate these autosomal genes independent of circulating sex hormones (7,8). The role of Imprinted genes in sexual orientation was corroborated by a genome-wide linkage analysis on gay-brother pairs that showed the presence of a maternally-expressed, paternally-silenced imprinted gene for sexual orientation in chromosome location 10 (9). Researchers from the genomic company 23andMe completed a genome wide association study of sexual orientation by screening 24000 individuals (self-report on sexual orientation) for genetic markers and found one close to the pericentromeric region of chromosome 8 (10). Conclusively, these molecular genetics studies indicate that sexual orientation genes have small effects individually and non-social environmental influences can shape up male sexual orientation. More studies with large sample size are needed to identify the genes that determine the sexual orientation (11,12).
Further, it is clear that Non-genetic factors can influence the development of homosexual behavior! A female embryo randomly inactivates one X chromosome early in development to create dosage compensation. A study published in 2006, showed that mothers of two or more gay sons demonstrated extreme skewing of X-chromosome inactivation (nonrandom pattern of X-inactivation) highlighting the role of X chromosome in regulating sexual orientation in males (13).Thus, the origins of sexual orientation need a lot more digging up before we can arrive at a conclusive result. However, years of efforts from scientists all around the world has led us to understand that homosexuality is not the exclusive result of social environment or a sickness. Sometimes people are born different (for several biological and environmental causes) and accepting them without doubt or caution is the best we can do to be better humans.
Additionally, it is clear that homosexuality is not regarded as an inherited thing and it has nothing to do with the family hereditary. In most cases it someone’s choice which is mostly contributed by the society and the group of people that one interacts with. Thus, it is true that gene sequence has nothing to do with homosexuality. However, it is also not true to say that hypothalamus plays a role in homosexuality because the acts of homosexual are usually brought by one’s characters that develop to behaviors. Additionally some research and human opinions such as the Boston psychiatrist Richard Pillard argued that homosexual is kind of biological diversity with some genes diverse however the nature denied that saying that genes do not make one become homosexual for example it is clear that no evidence of the family sharing a common ancestors are all homosexual hence indicating that genes are not in any way related to homosexual.
Moreover, only a few cases that can be reported that women with some form of congenital adrenal hyperplasia might be having masculinized genitalia that may make them develop heterosexual, however, there is no clear evidence that it has led to issues of gay or lesbianism, therefore it is clear that even though there is such case it is mostly related to the brain, however, no clear evidence built on it. Additionally, from the issue on the homosexual MZ and DZ twins indicates that there is not clear evidence nor significant reason that one can take to show what causes the homosexuality indicating that to some extent homosexuality is brought forward by unhealthy child upbringing, such as allowing children to have the relationship with people of opposite sex who end up frustrating one hence making one think that the opposite sex is bad hence opting for homosexual. Moreover, distorted concepts of another gender create one’s view towards the other gender hence making one lack any interest towards the opposite sex. Moreover, sexual abuse besides one peer pressure can also contribute to cases of homosexuality.
However, it can be concluded that there is no exact or known fact that brings about homosexuality because genetics, hormonal or even one’s cultures may not fully dictate the issue of homosexuality but in most research one’s care and nature might trigger one in becoming a homosexual. Thus, concluding that there is no research that shows one hundred per cent that homosexuality is related to any form of genes disorder, thus it is said to be a habit due to one’s peer group, upbringing and the environment where one grows. Besides the relationship that one has with the opposite sex may lead one to become a homosexual.
1.Bailey, J. M., Dunne, M. P., & Martin, N. G. (2000). Genetic and environmental influences
on sexual orientation and its correlates in an Australian twin sample. Journal of Personality and Social Psychology,78(3), 524-536. doi:10.1037//0022-35188.8.131.524
- Hamer, D., Hu, S., Magnuson, V., Hu, N., &Pattatucci, A. (1993). A linkage between DNA
markers on the X chromosome and male sexual orientation. Science,261(5119), 321-327. doi:10.1126/science.8332896
- Rice, G. (1999). Male Homosexuality: Absence of Linkage to Microsatellite Markers at
Xq28. Science,284(5414), 665-667. doi:10.1126/science.284.5414.665
- Levay, S. (1991). A difference in hypothalamic structure between heterosexual and
homosexual men. Science,253(5023), 1034-1037. doi:10.1126/science.1887219
- Allen, L. S., &Gorski, R. A. (1992). Sexual orientation and the size of the anterior
commissure in the human brain. Proceedings of the National Academy of Sciences,89(15), 7199-7202. doi:10.1073/pnas.89.15.7199
- Wisniewski, A., Kirk, K., & Copeland, K. (2008). Long-Term Psychosexual Development in
Genetic Males Affected by Disorders of Sex Development (46, XY DSD) Reared Male orFemale. Current Pediatric Reviews,4(4), 243-249. doi:10.2174/157339608787407663
- Rice, W. R., Friberg, U., &Gavrilets, S. (2012). Homosexuality as a Consequence of
Epigenetically Canalized Sexual Development. The Quarterly Review of Biology,87(4), 343-368. doi:10.1086/668167
- Morgan, D. K., & Whitelaw, E. (2008). The case for transgenerational epigenetic inheritance
in humans. Mammalian Genome,19(6), 394-397. doi:10.1007/s00335-008-9124-y
- Mustanski, B. S., Dupree, M. G., Nievergelt, C. M., Bocklandt, S., Schork, N. J., &Hamer,
- H. (2005). A genomewide scan of male sexual orientation. Human Genetics,116(4), 272-278. doi:10.1007/s00439-004-1241-4
- Drabant, E. M., Kiefer, A. K., Eriksson, N., Mountain, J. L., Francke, U., Tung, J. Y., . . .
Do, C. B. (2012). Genomewide association study of sexual orientation in a large, web based cohort. Poster presented at the 2012 Annual Meeting of the American Society of Human Genetics, San Francisco, CA. Retrieved from http://blog.23andme.com/wp-content/ uploads/2012/11/Drabant-Poster-v7.pdf
- Ngun, T. C., Ghahramani, N., Sánchez, F. J., Bocklandt, S., &Vilain, E. (2011). The
Genetics of Sex Differences in Brain and Behavior. Frontiers in Neuroendocrinology, 32(2), 227–246. http://doi.org/10.1016/j.yfrne.2010.10.001
- Homosexuality may be caused by chemical modifications to DNA. (2017). Science |
- Bocklandt, S., Horvath, S., Vilain, E., &Hamer, D. H. (2005). Extreme skewing of X
chromosome inactivation in mothers of homosexual men. Human Genetics,118(6), 691-694. doi:10.1007/s00439-005-0119-4
- Blanchard R.(1997) Birth order and sibling sex ration in homosexual versus heterosexual
males and females. Annual Review of Sex Research,8:27–67
- Bogaert, A. F., &Skorska, M. (2011). Sexual orientation, fraternal birth order, and the
maternal immune hypothesis: A review. Frontiers in Neuroendocrinology, 32, 247–254.,
- Piper, K. P., Mclarnon, A., Arrazi, J., Horlock, C., Ainsworth, J., Kilby, M. D., Moss, P. A.
(2007). Functional HY-Specific CD8 T Cells Are Found in a High Proportion of Women Following Pregnancy with a Male Fetus. Biology of Reproduction,76(1), 96-101. doi:10.1095/biolreprod.106.055426
- Skaletsky, H., Kuroda-Kawaguchi, T., Minx, P., Cordum, H., Hillier, L., & Brown, L. et al.
(2003). The male-specific region of the human Y chromosome is a mosaic of discrete sequence classes. Nature, 423(6942), 825-837. http://dx.doi.org/10.1038/nature01722
18.Schachner, M., &Ha¨mmerling, U. (1974). The postnatal development of antigens on
mouse brain cell surfaces. Brain Research,73(2), 362-371. doi:10.1016/0006-8993(74)91058-0
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