Sexuality determined by nature or nurture? Fruit fly gives the answer

Sexuality determined by nature or nurture? Fruit fly gives the answer
By Tom Anderson
05 June 2005


The long-running scientific debate about whether homosexuality is determined by nature or nurture is dramatically closer to resolution after new scientific evidence was published yesterday.

Biotechnologists have found evidence that sexuality is, after all, determined by genes and not environment. Researchers discovered a single "switch gene" that swaps the sexual orientation of males and females.

In the research, published yesterday, genetically altered male fruit flies spurned females and became attracted to other males. Genetically altered females engaged in complex male mating rituals, vibrating their wings, licking other female flies' genitalia and curling their backs ready for copulation. They rebuffed males that tried to mate with them.

The heated debate about the nature of gay sexual orientation has divided opinion for decades, with many gay men and women saying that they were born homosexual. Anti-homosexual activists say that gay sexual orientation is learnt and can be "cured" with psychological help.

The paper's lead author, Barry Dickson, senior scientist at the Austrian Academy of Sciences in Vienna, said: "We have shown that a single gene in the fruit fly is sufficient to determine all aspects of the flies' sexual orientation and behaviour," he said. "It's very surprising."

Dr Michael Weiss, chairman of biochemistry at Ohio University, was as surprised at the findings. "It seems that none of us chooses our sexuality. It just happens. The results are so clean and compelling, the whole field of the genetic roots of behaviour is moved forward tremendously by this work," he said.

"Hopefully this will take the discussion about sexual preferences out of the realm of morality and put it in the realm of science."

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