The science of… being gay


To celebrate Wadham College’s Queer Week, George Gillett explores the scientific theories behind diversity in sexual orientation

Sexual orientation puzzles scientists. Alongside campaigners, the scientific community has proposed numerous theories to try and explain the diversity among individuals, yet none have been proven.

An obvious starting point is genetics – after all, genes have been discovered which have strong links to a number of aspects of human behaviour, including substance abuse, obesity and even aggression. But could there be a gene for homosexuality? It does seem illogical that a characteristic which is counterproductive to reproduction (and hence the passing on of an individual’s genes) would’ve survived the ruthlessness of natural selection. Evolution arises because some genes are more likely to be passed on to offspring than others – and it therefore appears contradictory that homosexuality could have genetic causes.

Yet many evolutionary biologists claim the issue isn’t as simple as this. One ‘gay uncle’ theory claims that throughout evolution, individuals who didn’t have children aided the survival of their society by providing resources to other individuals in their family, since they lacked the burden of their own offspring. Therefore, the presence of a  ‘gay gene’ in a family’s DNA could’ve increased the chance of their offspring thriving and continuing to reproduce, suggesting that perhaps there are genetic causes to sexual orientation. However, this theory still lacks evidence of any genes that have been associated with homosexuality.

Other scientists suggest that sexual orientation may be linked to hormonal changes throughout the development of a foetus during pregnancy. While the development of genitalia has clear genetic causes (a section of DNA called the sex-determining region on the Y chromosome), the development of male and female brains is determined by exposure to sex hormones such as testosterone. Moreover, the gender determination of the genitals and brain occur at different intervals throughout pregnancy, suggesting that they can be influenced independently. This is the basis of many beliefs on the causes of transgenderism, and some scientists argue that hormones may be key to understanding sexual orientation as well.

However, it is possible that sexual orientation isn’t determined by genes or hormones, but the environment we grow up in. Human rights campaigner Peter Tatchell supports the idea that being gay is a result of a socialisation process, and there is some evidence to reinforce this view. For instance, homosexuals are five times less likely than heterosexuals to conform to gender stereotypes in childhood, and there is a correlation between an individual’s sexual orientation and the number of elder brothers they have. This data may seem convincing at first, but it is hard to determine whether the correlations indicate any significant causation. What is certain is that all of these theories lack substantial evidence, and more research is needed before making conclusive judgements.

Moreover, although scientists are eager to learn about sexual orientation, there is a danger that discoveries could be hijacked to make political statements. Whilst many individuals oppose homosexuality for supposedly being unnatural, a discovery that socialisation determines sexual orientation wouldn’t render the struggle for LGBTQ rights illegitimate. Consequently, the scientific community need to be careful on how they report their research.

Ultimately, sexual orientation is extremely diverse, and includes a huge variety of identities. Because of this, it is important to not treat the study of sexual orientation in the same way that diseases are investigated – homosexual behaviour is clearly not a problem which needs a cure. Therefore, the scientific community must understand the sensitivity of their research; to treat the issue of sexual orientation carelessly could prove both insulting and damaging.


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