Study Provides Insight Into Genetics of Same-Sex Behavior

23andMe reported that a new genome-wide association study (GWAS) involving more than 490,000 individuals, including 75,000 23andMe customers who consented to research, offers an intriguing glimpse into the complexity of sexual behavior. 

23andMe points out that the study found thousands of genetic variants with very, very, small affects on same-sex sexual behavior. It did not find any “gay gene”, nor did the researchers expect to.

The study included genetic samples from both 23andMe and UK Biobank. The researchers performed genome-wide association discovery analyses on 477,522 individuals from the United Kingdom and the United States, replication analyses in 15,142 individuals from the United States and Sweden, and follow-up analyses using different aspects of sexual preference.

The researchers concluded that same-sex behavior is influenced by not one or a few genes but many. Overlap with genetic influences on other traits provides insights into the underlying biology of same-sex sexual behavior, and analyses of different aspects of sexual preference underscore its complexity and call into question the validity of bipolar continuum measures such as the Kinsey scale. 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.

In other words, as 23andMe explains, the researchers did not find any patterns among genetic variants that could be meaningfully be used to predict or identify a person’s sexual orientation or behavior. In other words, it is not possible for a DNA test to determine if an individual heterosexual or is LGBTQ.

The researchers note that phenotypes are complex, and their genetic insights are rudimentary. They state that people should avoid simplistic conclusions because there is a long history of misusing genetic results for social purposes.

23AndMe explains that previous studies of this type were underpowered and under resourced, in part because recruitment of participants was difficult.

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