Biology alone doesn’t cause homosexuality, suggests new epigenetic research
Vladimir Putin, Robert Mugabe, Pope Francis and other anti-gay world leaders may well rejoice at new scientific research that points to homosexuality as being significantly influenced by pre- and post-birth environmental factors. They’ll no doubt see it as refuting claims that people are born gay and that same-sex attraction is immutable. They may be tempted to conclude that if homosexuality is not fully biologically determined, this research can be exploited to eradicate it.
But they’d be wrong. The degree and nature of these environmental influences is, as yet, unknown. They are likely to be multiple and complex. So any bid to abuse the new research and manipulate the environment to eliminate same-sex desire is unlikely to work.
The study by Dr Tuck C. Ngun and his team at the University of California found that an algorithm using epigenetic information from a mere nine regions of the human genome can predict the sexual orientation of males with up to 70 percent accuracy.
This suggests that environmental factors that switch genes on and off and affect how cells read genes may have a significant influence on human sexuality, both heterosexual and homosexual.
These environmental influences have not been identified but they may include hormones, chemical exposure, stress, diet, exercise, childhood interactions, peer pressure and social values. Nor is it clear whether these factors only have an impact pre-birth and in early childhood or whether they may also affect adults in later life.
The degree of environmental influence is still unclear. We already have plenty of previous research that points to likely significant biological drivers of sexual orientation. This includes ‘gay gene’ studies that have identified the Xq28 marker on the X chromosome as possibly associated with homosexuality; plus evidence of differences in the amygdala, hypothalamus and symmetry of the brains of gay and straight men.
Other research, which also indicates a genetic component to sexual orientation, has found that among identical twins where one brother is gay the likelihood of the other brother also being gay is much greater than the incidence of homosexuality in the general population (20-50% in identical twins, as opposed to 2-10% among the wider male population). But the fact that there is not a 100% concordance of gayness among identical twins suggests that factors other than genes play a role.
Research has further revealed differences between gay and non-gay men in physical attributes thought to be triggered by hormonal influences in the womb. These include differences in physique, brain structure, finger lengths, penis size (gay men tend to be better endowed than straight men), and the age of puberty (on average gay men mature earlier than heterosexual men). Other studies also found physiological variations between lesbian and straight women. Hormonal influences are generally accepted as significant but their degree of influences is not yet known.
While all these studies have been disputed to varying degrees by fellow scientists – as no doubt will Dr Ngun’s research – the preponderance of scientific evidence nevertheless does point to biological factors as probably being prime (but not exclusive and total) influences on sexual orientation.
If sexual attraction is, indeed, significantly fixed prior to birth or soon afterwards, whether by biological or environmental factors or a combination of both, it means that anti-gay regimes are persecuting lesbian and gay people for a sexual orientation that many or all of them have not chosen and cannot change. As well as being unethical, it is also means that attempts to suppress homosexuality won’t succeed because a certain percentage of every population is always likely to be predisposed from birth or early childhood to same-sex attraction.
There are, of course, still loose ends to Dr Ngun’s research and to all similar scientific studies. None of them identify a single cause of sexual orientation and none can explain everyone’s sexuality. This is because it seems that something as complex and varied as sexual orientation doesn’t have a sole determinant. It is likely to be multi-causal, including to some degree (even if minor) cultural factors, such as social mores and expectations.
No one sits down one day and decides to be gay – or straight. Most lesbians and gays say they felt “different” from a very young age, long before they had any awareness of sexual desire. While this suggests that our sexuality is formed unconsciously by early childhood at the latest – and is therefore not a choice – it does not necessarily mean we are all born with a totally pre-fixed sexual orientation.
Moreover, Dr Ngun’s study claims to be able to predict the sexual orientation of males with “up to 70 percent accuracy.” I get sceptical when I read “up to.” Even at a maximum of 70%, it still leaves 30% unpredictable.
Contrary to the way many people may interpret this study, biological and environmental influences, which I accept, are not the same as causes. They may predispose a person to one sexuality rather than another. But that’s all. Predisposition and determination are two different things.
There is a major problem with any theories that posit the biological or environmental programming of sexual orientation from pre-birth or in the years after birth. If heterosexuality and homosexuality are determined and fixed by early childhood – and therefore mutually exclusive and unchangeable – how do we explain bisexuality or people who, suddenly in mid-life, switch from heterosexuality to homosexuality (or vice versa)? We can’t.
The Kinsey researchers famously reported the case of a happily married young woman who, ten years into her marriage, unexpectedly fell in love with a female friend. Divorcing her husband, she set up house with this woman. Many years later, despite a fulfilling on-going lesbian relationship, she had an equally satisfying affair with a man. Examples of sexual flexibility, like that of this woman, don’t square with theories of rigid erotic predestination. They tend to support the thesis that environmental factors may affect sexual orientation.
If gayness was only explainable in biological terms we would expect it to appear in the same proportions, and in similar forms, in all cultures and all epochs. As the anthropologists Clellan Ford and Frank Beach demonstrated in Patterns Of Sexual Behaviour (1965), far from being cross-culturally uniform and stable, both the incidence and specific expressions of same-sex desire vary vastly between different societies. This variation gives credibility to the role of environmental factors suggested by Dr Ngun’s research.
Since a homosexual orientation seems likely to have a complex and diverse range of biological, environmental and cultural influences, homophobic bids to eliminate it look set to fail. Bravo!