I shoulda mentioned this, too. There is NO GAY GENE.
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Science
There’s (Still) No Gay Gene
by
Bennett McIntosh
8.29.19
Computer artwork by Alfred Pasieka/Science Source
There is no one gene for being gay, and though genes seem to play a role in determining sexual orientation and same-sex behavior, it’s small, complex, and anything but deterministic. That’s the conclusion of a paper by an international team of researchers, co-led by Benjamin Neale of the Broad Institute of Harvard and MIT, published today in the journal
Science. The team combed the genomes of more than 470,000 people in the United States and the United Kingdom to see how genetic variants at millions of different places in the genome correlate with whether participants had ever had sex with someone of the same sex. The study, by far the largest such investigation of sexuality to date, was made possible by combining genetic and behavioral data from more than 400,000 people from the UK’s
BioBank study, and from 70,000 customers of the genetic testing company
23andMe, who opted in to having their data used for research.
The researchers found five genetic variants—changes at a single site in the DNA sequence—that correlated with same-sex sexual behavior: two of these had a significant effect only in males, and one only in females.
The effect of each variant is small and inconsistent: for example, the authors note that in one of the male-specific variants, subjects who had a thymine molecule (“T”) at a particular spot in the genetic sequence on chromosome 11 have a 3.6 percent likelihood of having had sex with other males, while subjects who had a guanine molecule (“G”) there had a likelihood of 4 percent. The other four significant variants (on chromosomes 4, 7, 12, and 15) showed similar, or even smaller, effects.
“It’s effectively impossible to predict an individual’s sexual behavior from their genome,” said Neale, the director of genetics in the Stanley Center for Psychiatric Research at the Broad and an associate professor in medicine at Harvard Medical School (HMS), during a Tuesday teleconference introducing the paper’s findings. In fact, the team estimated that the genetic variants they studied could predict, at best, somewhere between 8 percent and 25 percent of the reported variation in the entire cohort’s sexual behavior. (The idea that a binary variable—i.e., whether a male has or has not had sex with another male—might itself have a “variation” may seem counterintuitive, but this number is analogous to estimating that 50 percent of the variation in a certain population’s height can be attributed to genes—it refers to the differences
within the population, not the genetic contribution to any individual’s traits). The rest comes down to the expansive realm of “non-genetic” or “environmental” effects—which Neale said “can range from anything in utero all the way through to who you happen to stand next to on the Tube in the morning.”'
Genes seem to play a role in determining sexual orientation, but it’s small, uncertain, and complicated.
www.harvardmagazine.com
