Tomorrow’s issue of Science will feature a study that undermines the strongest claim of a genetic component in male homosexuality.  

Researchers from the Department of Genetics at Stanford Medical School and the Department of Clinical Neurological Sciences at the University of Western Ontario concluded that “data do not support the presence of a gene of large effect influencing sexual orientation.”

In a 1993 study, also published in Science, homosexual activist and researcher Dr. Dean Hamer of the National Cancer Institute suggested a link between genes and homosexuality. Homosexual activists have used Hamer’s research to promote everything from so-called same-sex marriage to hate crimes legislation.  

Because the new study was larger, including more pairs of homosexual siblings than Hamer’s study did, it had the power to replicate Hamer’s results.  However, the new study’s authors write that they “found no evidence of linkage to sexual orientation” in the genetic position where it had been asserted before.  This new study reveals that Hamer’s activism got in the way of his ability to remain unbiased about his research.

Science is telling us what we have always known: There is absolutely no scientific proof of a “gay gene.”

WASHINGTON - In a study that attacks U.S. researchers’ hunt for a “gay gene,” Canadian scientists are questioning whether a gene inherited from mothers influences men’s sexual orientation.

Scientists still can’t explain what determines a person’s sexual orientation, although many studies have suggested that it is biology and not choice.

The first such evidence came in 1991, when researchers discovered that identical twins of gay men were much more likely to also be gay than were fraternal twins.

Then National Cancer Institute geneticist Dean Hamer made headlines in 1993 by suggesting that one such gene resides in a region of the X chromosome, one of the microscopic structures that carry genes.  Men inherit that chromosome from their mothers. 

Although Hamer never identified the gene itself, his research suggested its location by finding that 33 pairs of gay brothers shared certain genetic “markers” that heterosexual brothers didn’t.

But in a report to be published today in the journal Science, Canadian scientists said they tried to reproduce Hamer’s study and found no link.

Neurologist George Rice of the University of Western Ontario studied gay brothers from 48 families and said they were no more likely to share X-linked genetic patterns than would be determined by chance.

That doesn’t mean genes don’t influence homosexuality, Rice said, just that scientists should hunt elsewhere.  “We are still looking,” he said. 

Hamer vehemently defended his research, saying other scientists have found evidence supporting it.  “This study doesn’t disprove that,” he said.