Researchers claim they have found a link between genetic make-up and sexual orientation, but scientific experts have pointed out major flaws.
A team of researchers claims it has found a link between genetic make-up and sexual orientation. In a paper published by Scientific Reports, the scientists from the U.S., the UK, and Australia wrote that they had found two gene variants that appear to be more prevalent in men who identify as homosexual.
The researchers looked into the DNA of approximately 1,000 homosexual men, comparing it to genetic data from a similar number of heterosexuals, and claimed to have found that the DNA was different for “gay” and heterosexual men in at least two genes.
In addition to providing DNA for analysis, study participants were rated for sexual orientation based on their self-reported sexual identity and sexual feelings.
As reported by MedicalExpress.com, one of the identified genes “is located on chromosome 13, which prior research has shown has an impact on the diencephalon, a part of the hypothalamus — a part of the brain shown to be differently sized between gay and straight men.”
The other gene was found on chromosome 14, “which prior research has shown is mainly involved with the thyroid, though it does also have an impact on the brain via a protein involved in stimulating the thyroid. Some prior studies have led to findings that suggest the thyroid might also be involved in sexual orientation.”
While many in the homosexual community have been anxious to use the research as proof that homosexuality is genetically determined, scientists critical of the study emphasized that no such determination could be made. They pointed out, for instance, that the sampling of 1,000 self-identified homosexual men was small for such a study, along with the fact that many of the self-identifying homosexual participants were recruited at “gay pride” events, virtually all were caucasian, and men who identified as bisexual were excluded from the study.
“The sample size is small, the results have not been replicated in an independent study, and the level of evidence presented doesn’t meet the threshold of significance typically required within the field,” Gil McVean, a statistical geneticist at the University of Oxford, wrote in comments for the paper. “I don’t think the work would have been published if it were on a less controversial topic. It is—at best—preliminary.”
Another critic of the research findings, developmental biologist Robin Lovell-Badge of London’s Francis Crick Institute, argued that all the study really demonstrates is that the identified gene regions varied between the two groups of men, with one group self-identifying as homosexual.
“Even if a gene variant does show some correlation with sexual orientation, this does not mean that the gene is in any way responsible for being gay,” he wrote. “It just means it has some association with a trait that is more likely to found in the relatively few people involved as subjects in the study. This could be better social awareness or being brave enough to acknowledge that they are in a minority.”
McVean added that sexuality “is likely influenced by many different factors, including environment, experience and, likely, some aspects of innate biological variation. I can see no major implications of this work or how it could be useful in the future. The genetic effects are far too weak to be of any predictive or diagnostic value. All biology — including the origins of sexuality — is interesting at some level, but I see no direct applications of such research.”
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