Sexual orientation is described as our patterns of emotional and sexual attraction, with the American Psychological Association further highlighting an emanating sense of personal and social identity, based on those attractions. Alas, the understanding and acceptance of sexuality has, historically, not always been favourably embraced; until 1973, the very same American Psychological Association perceived homosexuality as a mental disorder. Although we’ve moved on in non-homophobic leaps and bounds – where sexual orientation is now no longer considered a ‘choice’ – the psychology of sexual orientation is still heavily debated.
The nature versus nurture debate is inescapable in many areas of Psychology, however there are very few issues which are as hotly contested as the determination of a person’s sexual orientation. Debate on the origins of sexual orientation is made all the more convoluted by the fact that sexuality is not a concrete concept; it exists on a continuum, rather than a strict dichotomy of homosexual or heterosexual.
The ‘nurture’ face of the coin lands on a side which argued that developmental elements, occurred during childhood, are one of the significant contributing factors to homosexuality. As such, the roles of domineering mothers and ineffectual fathers dominated the thinking of psychologists who subscribed to this area of debate. This theory was however based on very little scientific evidence and – rather like the once popular notion that ‘refrigerator mothers’ cause their children to be autistic – has largely been discredited. In fact, the role of mothers in determining sexual orientation is more likely to be related to factors such as sex hormones levels; lower amounts of prenatal testosterone have been linked to homosexuality.
One area of research which provides the perfect arena for separating the influences of genetic and environmental factors on sexuality, are twin studies. The general finding from these studies is that the concordance rate for homosexuality in identical twins is roughly 50%, compared to approximately 20% in fraternal twins. Given that twins are usually treated similarly, this difference is likely a result of identical twins sharing all of their genes, whilst fraternal twins share only half of them. However, as the concordance rate in identical twins is not 100%, it would be hasty – and indeed false – to claim that environmental factors don’t exert some influence. Additionally, genetic linkage studies have shown that, in the case of homosexual males, there are more homosexual men on the mother’s side. This has led to homosexuality being identified as an X-Chromosome linked trait – with the specific related gene, Xq28, being dubbed the ‘gay gene’.
Evidence of a biological basis for homosexuality also comes from brain differences. Sexual orientation cannot simply relate to differences in the brain’s activity patterns; your sexuality is unlikely to have altered after waking from a night’s sleep or even a coma. Differences in sexual orientation must therefore, somehow, relate to differences in the actual anatomical structure of the brain. For example, structures in the hypothalamus – the section of the brain that relates to sexual drive and function – differ in size for homosexual and heterosexual males. However, not all of these structures, which develop prenatally during the process of sexual differentiation, are involved in the brain’s regulation of sexual behaviour. This suggests that potentially key components of our brain’s development, with regards to sexual orientation, occur prior to birth and that in terms of sexuality, size really doesn’t matter.
The science suggests that far from being an actively made choice, homosexuality is actually the result of things we don’t choose, things out of our control – our genes, upbringing, and hormones. Clearly, finding evidence in support of homosexuality’s ‘biological basis’ should only make us more vigorous in promoting LGBT rights.
Image courtesy of The Blue Diamond Gallery.