Source: Andrea Ganna, "Large-scale GWAS reveals insights into the genetic architecture of same-sex sexual behavior," Science Magazine, 30 August 2019
The claim is that they found five possible influences toward homosexual behavior in DNA, but at the same time the report is full of qualifiers.
"In aggregate, all tested genetic variants accounted for 8 to 25% of variation in male and female same-sex sexual behavior, ... These aggregate genetic influences partly overlapped with those on a variety of other traits, including externalizing behaviors such as smoking, cannabis use, risk-taking, and the personality trait 'openness to experience.'"
In other words, these influences don't tell us much about a person's actual sexual behavior and that what could be measured is a person's willingness to engage in risky behavior. (Though I doubt that is genetically governed.)
"In aggregate, all tested genetic variants accounted for 8 to 25% of variation in same-sex sexual behavior, only partially overlapped between males and females, and do not allow meaningful prediction of an individual’s sexual behavior."
"We established that the underlying genetic architecture is highly complex; there is certainly no single genetic determinant (sometimes referred to as the “gay gene” in the media). ... All measured common variants together explain only part of the genetic heritability at the population level and do not allow meaningful prediction of an individual’s sexual preference."
Source: Lindsey Tanner, "New genetic links to same-sex sexuality found, but no specific gene, new study shows," Chicago Tribune, 29 August 2019.
"... it echoes research that says there are no specific genes that make people gay."
"The researchers said thousands more genetic variants likely are involved and interact with factors that aren't inherited, but that none of them cause the behavior nor can predict whether someone will be gay."
"We also found that it's effectively impossible to predict an individual's sexual behavior from their genome."
"A Science commentary notes that the five identified variants had such a weak effect on behavior that using the results 'for prediction, intervention or a supposed 'cure' is wholly and unreservedly impossible.'"
"Former National Institutes of Health geneticist Dean Hamer said the study confirms "that sexuality is complex and there are a lot of genes involved," but it isn't really about gay people. "Having just a single same sex experience is completely different than actually being gay or lesbian," Hamer said. His research in the 1990s linked a marker on the X chromosome with male homosexuality. Some subsequent studies had similar results but the new one found no such link."
It is significant that this study yields evidence that past studies were inaccurate. What we are left with is a continued claim that there might be a tendency toward homosexual behavior that is genetically based but that genetics cannot predict actual behavior.