A few years ago, Dr James Watson, the Noble Prize winner who co-discovered DNA, reopened the controversy over the so-called gay gene when he defended a woman’s right to abortion.

He was quoted in The Sunday Telegraph as saying: “If you could find the gene which determines sexuality, and a woman decides she doesn’t want a homosexual child, well, let her (abort the foetus)”.

Much of the reaction to Dr Watson’s statement focused on its homophobic versus freedom of choice implications.

Largely overlooked was the fact that such an esteemed scientist was giving credibility to the flawed theories which claim a genetic causation of homosexuality.

These theories have been given a recent boost by research suggesting differences in the brain structures of gay and straight people.

According to gay gene theory, genetic factors are responsible for sexual orientation, with our genetic inheritance programming us to desire one sex rather than the other.

This is a very simple, deterministic thesis: A causes B.

I don’t disagree that genes (and hormonal exposure in the womb) influence sexual orientation.

The scientific evidence for these biological influences is presented in the book, Born Gay (2005), written by Glenn Wilson of the Institute of Psychiatry in London and Qazi Rahman, a lecturer in psychobiology at the University of East London.

But contrary to what the authors seem to suggest, an influence is not the same as a cause.

Genes and hormones 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 gay gene theory, and with all theories that posit the biological programming of sexual orientation.

If heterosexuality and homosexuality are, indeed, genetically predetermined (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 reality is that queer and straight desires are far more ambiguous, blurred and overlapping than any theory of genetic causality can allow.

After studying the sexual experiences of thousands of men, Dr Alfred Kinsey presented evidence, in Sexual Behaviour In The Human Male (1948), that “many males combine in their single histories, and very often in exactly the same period of time, or even simultaneously in the same moment, reactions to both heterosexual and homosexual stimuli”.

Some years later, 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 genetic theories of rigid erotic predestination.

One of the main original proponents of gay gene theory, Dr Dean Hamer, now concedes that it is unlikely that something as complex as human sexuality can be explained solely in terms of genetic inheritance.

He seems to accept that while genetic factors may establish a predisposition towards homosexuality a predisposition is not the same as a causation.

Many studies suggest social factors are also important influences in the formation of sexual orientation.

These include the relationship between a child and its parents, formative childhood experiences, family expectations, cultural mores and peer pressure.

By about the age of five or six, a combination of biological and social influences seem to lay the basis of an individual’s sexual orientation.

Because our sexuality is fixed at such an early age, many lesbians and gay men feel they have been homosexual all their lives and therefore mistakenly conclude that it must be genetic and that they were born queer.

They also see the gay gene explanation as a useful defence against the arguments of the religious right, which dismisses same-sex relationships as a lifestyle choice.

But no one sits down one day and chooses to be gay (or straight).

Sexual orientation is not a choice like choosing which biscuits to buy in a supermarket.

We don’t have free will concerning the determination our sexual orientation. Our only free will is whether we accept or repress our true inner sexual and emotional desires.

The relative influence of biological versus social factors with regard to sexual orientation is still uncertain.

What is, however, certain is that if gayness was primarily explainable in genetic 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 expressions of same-sex desire vary vastly between different societies.

They found, for example, that young men in some tribes (the Aranda of Australia, Siwan of Egypt, Batak of Sumatra, Anga of Melanesia and others) had relationships with boys or older male warriors, usually lasting several years, often as part of manhood initiation rituals.

Eventually ceasing homosexual contact, they subsequently assumed sexual desires for women.

If sexual orientation was genetically prefixed at conception, as the proponents of the gay gene claim, these young men would never have been able to switch between heterosexual and homosexual relations with such apparent ease.

Likewise, a glance at history reveals huge disparities between configurations of homosexuality in different eras down the ages.

Same-sex behaviour in Ancient Greece was very different, in both its prevalence and particular manifestations, from homosexuality in Confucian China, Renaissance Italy, Meiji Japan, Tudor England and late twentieth century USA.

Moral values, social ideologies and cultural expectations – together with family patterns and parent-child interaction – seem the only credible explanation for these massive historical divergences.

Despite obvious theoretical and empirical weaknesses, the claims that certain genes cause homosexuality have been seized upon and vigorously promoted by many in the lesbian and gay rights movement (especially in the US).

The haste with which these unproven, questionable theories have been embraced suggests a terrible lack of self-confidence and a rather sad, desperate need to justify queer desire.

It’s almost as if those pushing these theories believe we don’t deserve human rights unless we can prove that we are born gay and that our homosexuality is beyond our control: ‘We can’t help being fags and dykes, so please don’t treat us badly’. This seems to be the pleading, defensive sub-text of much of the pro-gay gene thesis.

Surely we merit human rights because we are human beings?

The cause of our homosexuality is irrelevant to our quest for justice. We are entitled to dignity and respect, regardless of whether we are born queer or made queer, and irrespective of whether our homosexuality is something beyond our control or something freely chosen.

The corollary of the ‘born gay’ idea is the suggestion that no one can be ‘made gay’.

This defensive argument was used by some gay leaders during the campaigns against Section 28, which banned the “promotion” of homosexuality by local authorities, and again during the lobbying of parliament for the equalisation of the age of consent.

Supporters of Section 28 and opponents of an equal age of consent justified their stance with the claim that people need to be protected against ‘pressure’ and ‘seduction’ into the homosexual lifestyle.

Some gay spokespeople responded by arguing that it’s impossible to ‘make’ someone gay, and that a same-sex experience at an early age cannot ‘persuade’ a heterosexual person to become homosexual.

At one level, they are right. Sexual orientation appears to become fixed in the first few years of life. For most of us, it is impossible to subsequently change our sexual orientation.

However, what definitely can change as people grow older is their ability to accept and express formerly repressed queer desires.

A person who is ostensibly heterosexual might, in their mid-30s, become aware of a previously unrecognised same-sex attraction that had been dormant and unconscious since childhood.

Society’s positive affirmation of homosexuality might help such a person discover and explore those latent, hidden, suppressed feelings.

The homophobes are thus, paradoxically, closer to the truth than many gay activists. Removing the social opprobrium and penalties from queer relationships, and celebrating gay love and lust, would allow more people to come to terms with presently inhibited homoerotic desires.

In this sense, it is perfectly feasible to ‘promote’ lesbian and gay sexuality and ‘make’ someone queer.

Individuals who have a homosexual component in their character, but are inhibited by repression or guilt, definitely can be encouraged to acknowledge their same-sex attraction and act upon it.

Were future generations to grow up in a gay-positive, homo-friendly culture, it’s likely that many more people would have same-sex relationships, if not for all of their lives at least for significant periods.

With this boom in queer sex, the social basis of homophobia would be radically undermined.

In this state of greater sexual freedom, where homosexuality becomes commonplace and ceases to be disparaged or victimised, gayness would no longer have to be defended and affirmed.

Gay identity (and its straight counterpart) would thus, at last, become redundant. Hurrah!

This article by gay activist and human rights defender Peter Tatchell first appeared on spiked, “an independent online phenomenon dedicated to raising the horizons of humanity by waging a culture war of words against misanthropy, priggishness, prejudice, luddism, illiberalism and irrationalism in all their ancient and modern forms.”