Giant study links DNA variants to same-sex behaviorBy Michael PriceOct. 20, 2018 , 10:25 PM
SAN DIEGO, CALIFORNIA—How genes influence sexual orientation has sparked debate for at least a quarter-century. But geneticists have had only a handful of underpowered studies to address a complex, fraught, and often stigmatized area of human behavior. Now, the largest-ever study of the genetics of sexual orientation has revealed four genetic variants strongly associated with what the researchers call nonheterosexual behavior. Some geneticists are hailing the findings as a cautious but significant step in understanding the role of genes in sexuality. Others question the wisdom of asking the question in the first place.
Andrea Ganna, a research fellow with the Broad Institute in Cambridge, Massachusetts, and Harvard Medical School in Boston, and colleagues examined data from hundreds of thousands of people who provided both DNA and behavioral information to two large genetic surveys, the UK Biobank study and the private genetics firm 23andMe. They analyzed DNA markers from people who answered either “yes†or “no†to the question, “Have you ever had sex with someone of the same sex?†In total, they identified 450,939 people who said their sexual relationships had been exclusively heterosexual and 26,890 people who reported at least one homosexual experience.
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The researchers performed a genome-wide association study (GWAS) in which they looked for specific variations in DNA that were more common in people who reported at least one same-sex sexual experience. They identified four such variants on chromosomes seven, 11, 12, and 15, respectively.
Two variants were specific to men who reported same-sex sexual experience. One, a cluster of DNA on chromosome 15, has previously been found to predict male-pattern baldness. Another variant on chromosome 11 sits in a region rich with olfactory receptors. Ganna noted that olfaction is thought to play a large role in sexual attraction.
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https://www.sciencemag.org/news/2018/10/giant-study-links-dna-variants-same-sex-behavior
