It empowered a movement but existed only in their heads? A huge study involving nearly half a million people suggests so.
The largest study to date on the genetic basis of sexuality has revealed five spots on the human genome that are linked to same-sex sexual behaviour — but none of the markers are reliable enough to predict someone’s sexuality.
The findings, which are published on 29 August in Science and based on the genomes of nearly 500,000 people, shore up the results of earlier, smaller studies and confirm the suspicions of many scientists: while sexual preferences have a genetic component, no single gene has a large effect on sexual behaviours.Jonathan Lambert, “No ‘gay gene’: Massive study homes in on genetic basis of human sexuality” at Nature
This is probably not the result many were looking for or could even report straightforwardly:
The five genes each explained less than 1 percent of the variation in whether or not an individual reported participating in same-sex behaviors. When they included all sequences in the genome associated with same-sex sex, the researchers estimated that genes account for a maximum of 8–25 percent of the variation in the population’s behaviors, suggesting that much of what drives sexual activity is beyond genetics.
“Genetics is less than half of this story for sexual behavior but it’s still a very important contributing factor,” Ben Neale, a behavioral geneticist at the Broad Institute and a senior author on the study, said during the press conference. Still, the genetic associations he and his colleagues observed could not predict the likelihood that an individual would report having sex with partners of the same sex.Emma Yasinski, “Giant Study Helps Clarify Role of Genes in Same-Sex Sex” at TheScientist
Some simply deny the obvious conclusion:
However, the finding that there’s no single gay gene does not mean that sexual orientation is not genetic or biological, and is therefore a lifestyle choice.
“This is wrong,” study co-author Brendan Zietsch, a geneticist at the University of Queensland in Australia, told Live Science. “We find that there are many, many genes that predispose one to same-sex sexual behavior. Each of them individually has a very small effect, but together they have a substantial effect.
“Another possible misinterpretation is to think that if same-sex preference is genetically influenced, it must therefore be totally genetically determined,” Zietsch added. “That is not true. Genetically identical individuals — twins — often have different sexual orientations. We know there are non-genetic influences as well, but we don’t understand these well, and our study does not say anything about them.”Charles Q. Choi, “The ‘Gay Gene’ Is a Total Myth, Massive Study Concludes” at LiveScience
Identical twins having the same sexual orientation used to be the gold standard for claims about the gay gene so if the researchers are backing away from that, we can be sure that the case for genetic determinism about sexual orientation is in ruins, even if this researcher insists that that is the “wrong” interpretation.
Why are people so uncomfortable with the idea that they are not ruled by their genes?
Bet we haven’t heard the last of this.
See also: There’s a gene for that… or is there?
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