Literature review (homosexuality) Essay
Literature review (homosexuality)
The debate on homosexuality is certainly not a new one. Conservatives describe homosexuality as a ‘crime against nature’ whereas liberals shrug it off as a matter of personal sexual choice. While this debate is going to take long to come to a conclusion, new scientific researches are coming up to explain what actually causes homosexuality. New evidence that is coming suggests that there may be a genetic basis of homosexuality. In this review, we evaluate six articles each of which tries to explore the factors that contribute to homosexuality.
In their article “Human sexual orientation has a heritable component”, Richard C. Pillard and J Michael Bailey allege that homosexuality may have to be concealed due to community expectations. Sexual orientation of a person can be determined through reliable questionnaires and similar tests. However, the origin of homosexuality is difficult of determine due to the large number of variables involved. The first systematic study on the genetic basis of homosexuality came in 1986 by Pillard and Weinrich. They recruited volunteers and their siblings and both the groups were subjected to interviews and tests by different interviewers to remove bias. It was found that non heterosexual individuals had more non heterosexual siblings. Pillard et al (1981, 82) and Hamer et al (1993) found that gay/lesbian relatives of males were generally from the maternal side. This suggests the genetic origin of homosexuality. Twin studies are most common means of discussing whether any personality trait has genetic basis or not. Bailey and Pillard (1991) and Bailey, Pillard et al (1993), on conducting studies on gays with twins (MonoZygotic or DiZygotic) and gays with adopted siblings found that 52% of the MZ twins, 22% of the DZ twins and 11% of the adopted siblings showed homosexual characteristics. In females, the figures were 48% for MZ, 16% for DZ and 6% for adopted sisters. Three sets of triplets in the Whitam et al (1993) study gave insightful results. One triplet had a MZ male pair- both homosexual and a heterosexual sister. Second set had an MZ female pair- both lesbians and a DZ heterosexual sister. The third set had MZ brothers and all three were gays.
In another article “Opposite sex twins and adolescent same sex attraction”, by Peter S Bearman and Hannah Bruckner concludes that adolescent males opposite sex twins are twice as likely to report same sex attraction. It also puts forward the view that genetic influence independent of social context cannot be the causative factor of homosexuality. It is found that socially sanctioned heterosexual behavior is positively reinforced by parents and gender appropriate behavior is encouraged (Huston, 1983). However, genetic influence hypothesis cannot be conclusively proved because different studies show widely different concordance rates for MZ, DZ twins and stepsiblings. Also heredity estimates also vary widely. This is so because twin studies suffer from many biases such as identical upbringing of twins (especially MZ) during childhood, MZ twins being more likely to participate in twin studies (McGuire 1995; Lykken, McGue and Tellegen 1987) and males being more likely to participate than females. Thus this article strongly supports the view that even if genetic expression is present, it must be very strongly conditioned by socio- cultural influence. Also intrauterine transfer of hormones does not affect sexual orientation and there is substantial evidence in support of the socialization model of homosexuality.
The article “The Complexity of Sex” takes the debate a lot further by discussing the findings of an Italian group. These findings indirectly offer some support to the genetic theory of homosexuality. Dean Hamer’s discovery of the gay gene in 1993 was a huge boost for the genetic theory but it also created questions regarding the passing of gay gene down the family tree. It was argued that since gay men are less likely to have children, the gay gene should have disappeared according to Darwin’s theory of evolution. That the gay gene still persists is thus a paradox. The Italian group mentioned above, found that mothers and maternal aunts of gay men were likely to have more children than those of straight men. This overrides the paradox and also fits in well with the idea that the gay gene is found on the X- chromosome and is passed over from mother to son. However, the findings of the Italian groups also include that gay men were more likely to be either first born or have more older brothers than sisters. Thus, once again, we find that homosexuality is not purely genetic.
Udo Schuklink, Edward Stien, Jacinta Kerin and William Byne in “The Ethics of Genetic Research on Sexual Orientation” argue that the very idea of research on the origin of homosexuality is ethically wrong and is a danger sign for the already legally unprotected homosexual people. When all data are considered, the writers come to the conclusion that homosexuality is a complex trait which has genetic as well as socio- cultural basis.
“What makes people gay” by Neil Swidey raises the point that proving people are born gay will do a lot for social acceptance and tolerance of homosexuality. Citing the study by LeVay (1991) which indicated differences in the hypothalamus of gay and straight men and the study by Dean Hamer (1993) which claimed the discovery of the ‘gay gene’, this article propagates the biological basis of homosexuality. Twin brothers Patrick and Thomas (names changed) form a very important part of this article and of the debate as a whole. Thomas and Patrick were born and brought up in the same environment but Patrick shows signs of CGN (Childhood Gender Nonconformity) and thus displays feminine traits. In this regard, a New York researcher Lynn S Hall has hypothesized that Patrick was probably prenatally stressed during the first trimester and these differences in the prenatal environment determined Patrick’s gender atypical behavior.
Rosaro, Vernon in “New Gene Theory Rests on Bad Science” completely refutes the article by Michael Bailey. Vernon says that Bailey’s research is biased (based only on gay adults) and that all the traits that Bailey considers to be associated with homosexuality could as well be learned or acquired. Cultural differences may also affect classification of personality characteristics as ‘typically gay’ or ‘straight’. The article however, does not take a clear stand on the debate of in- born or acquired.
We had hypothesized in the beginning that homosexuality has a genetic basis. However, all the evidence taken together suggests that homosexuality is, in fact, a trait that results due to complex combinations of a moderate genetic influence and a huge socio- cultural impact. Thus it not genetics alone that accounts for homosexuality but genetics in combination with the environmental factors (especially during childhood) determines homosexuality.
Pillard, Richard C and Bailey, J Michael, “Human Sexual Orientation has a Heritable Component”, April 1998, Detroit, Human Biology, Vol. 70, 347 retrieved on 14 November, 2005 from
Rosario, Vernon, “New Gene Theory Rests on Bad Science”, Nov/Dec 2003, Boston, The Gay and Lesbian Review Worldwide, Vol. X, Iss. 6, 34 retrieved on 14 November, 2005 from
Breaman, Peter S and Bruckner, Hannah, “Opposite-Sex Twins and Adolescent Same-Sex Attraction”, March 2002, Chicago, The American Journal of Sociology, Vol. 107, Iss. 5, 1179, retrieved on 14 November, 2005 from
Anonymous, “The Complexity of Sex”, Oct 16- 22, 2004, London, New Scientist, Vol. 184, Iss 2649, 3, retrieved on 14, November 2005 from
Udo Schuklink, Edward Stien, Jacinta Kerin & William Byne, “The Ethics of Genetic Research on Sexual Orientation”, Jul/ Aug 1997, Hastings- on- Houston, The Hastings Centre Report, Vol. 27, Iss. 4, 6 retrieved on 14 November, 2005 from
Swidey, Neil, “What Makes People Gay”, August 14, 2005, Boston, Boston Globe, 33 retrieved on 14 November, 2005 from