Researchers from Harvard University and the Massachusetts Institute of Technology (MIT) teamed up to study the genetic profiles of almost half a million people. The researchers were looking for genetic factors that might indicate a person has a biological predisposition to same-sex behavior. Their conclusion: There is no such thing as a “gay gene.”
“There is no single gay gene, and a genetic test for if you’re going to have a same-sex relationship is not going to work,” says Ben Neale, an associate professor in the Analytic and Translational Genetics Unit at Massachusetts General Hospital. Neale worked on the study and says that while genetics is an important “contributing factor” for sexual behavior, it accounts for “less than half of this story.”
Scientists have long debated whether same-sex attraction and behavior is the result of nature or nurture, but there has yet to be any definitive evidence one way or the other. Previous studies such as a Johns Hopkins study on homosexuality have come to similar conclusions as this most recent study does. “There is virtually no evidence that anyone, gay or straight, is ‘born that way’ if that means their sexual orientation was genetically determined. But there is some evidence from the twin studies that certain genetic profiles probably increase the likelihood the person later identifies as gay or engages in same-sex sexual behavior,” a report published in The New Atlantis reads.
How Was the Research Conducted?
This most recent study’s results were published in Science magazine in an article titled “How do genes affect same-sex behavior?” Researchers analyzed the genomes of 408,995 individuals from the United Kingdom’s Biobank project and 68,527 individuals from the United States who have used 23andMe’s services. The article is diligent to point out that while this is a significant number of genomes to analyze, the results should be taken with a grain of salt due to the lack of diversity among the individuals represented by the data. The article explains:
A caveat common to most genetic discoveries is that the study…includes only European-ancestry populations from Western high-income countries (United Kingdom, United States, and Sweden for replication). The data also come from older individuals living under stricter social norms and legislative regulations (23andMe, mean age 51.3 years; UK Biobank, aged 40 to 69 years), overrepresented by higher socioeconomic status groups.
What Did the Study Find?
The study did find certain genetic variants associated with same-sex attraction, although the researchers say those variants can only account for 8-25 percent of same-sex behavior among the people it analyzed. There were five variants the researchers found, one of which being related to a person’s sense of smell. Other variants were linked to the body’s regulation of testosterone and estrogen.
The study represents the largest number of genomes analyzed with same-sex behavior in mind, and while there isn’t much the researchers can conclude at this time, it highlights the need for more research to be done on this topic. The article in Science concludes: “This study serves as a guide to the potential magnitude of genetic effects we may eventually measure and a sign that complex behaviors continue to have small, likely polygenic, influences.”