In a June 24 column for Spiked Online, Tatchell wrote: "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," he said. Nevertheless, "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," he went on.

"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."

Furthermore, "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." However, "far from being cross-culturally uniform and stable, both the incidence and expressions of same-sex desire vary vastly between different societies."

Indeed, the gay activist added, many studies suggest that "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 defense 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 of our sexual orientation. Our only free will is whether we accept or repress our true inner sexual and emotional desires."

Tatchell criticizes gay genetic determinism as suggestive of "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."

Tatchell agreed with conservative arguments that the reduction of social pressures against homosexuality would lead more people with a deep-seated same-sex tendency to act upon it: "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 unrecognized 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."

NEVERTHELESS, in the heat of debate recently with Evangelical Anglican e-journalist David Virtue of VirtueOnline, Tatchell seemed to backpedal somewhat, saying that a majority of the influence on sexual orientation comes from genes and from the prenatal hormonal environment.

In an August 3 forum on BBC Radio, Tatchell said, "All the scientific evidence now shows that there is a very significant, possibly a majority, influence, based on our genetic inheritance and hormonal influences in the womb.

There's masses of scientific evidence that show that sexual orientation is down to genes and hormonal influences...There's hundreds and hundreds and hundreds of studies from all over the world ... "You cannot say that gay people just willfully go out and decide to be gay and choose to lead this lifestyle; that is scientifically refuted. ... It is absolutely wrong for the church to denounce, condemn, and ostracize gay people who do not have the freewill choice over their sexual orientation."

Sources: Spiked Online, Wikipedia, BBC Radio Roundtable, www.virtueonline.org