National Geographic News
New research suggests that our genes partially determine whether we become social butterflies or wallflowers, calling into question the amount of choice we have in something as deeply personal as our friendships.
James Fowler, a political scientist at the University of California, San Diego, is the lead author of a study that says about half or our social networking style is written in our DNA.
"No one has ever drawn the link between genes and social networks before," Fowler said. "It suggests a whole new field of inquiry."
In other studies, Fowler and his colleagues have shown that nicotine addiction and obesity can ripple through social groups like plagues. We are influenced in such lifestyle choices by people we've never met—friends of friends up to three degrees of separation away. Happiness and smoking cessation can spread the same way.
Now, Fowler says, he may be closing in on a cause-and-effect cycle that could give people opportunities to change these aspects of their lives.
"Social networks might be the conduit between genes and these health outcomes," he said.
The new study, which appears in this week's issue of the journal Proceedings of the National Academy of Sciences, analyzed 1,110 adolescent twins from 142 schools.
The social networks of identical twins, who share the same genes, were more similar than those of fraternal twins, whose genes differ, indicating a genetic underpinning.
Based on the study, genes are about 50 percent responsible for both our number of friends and whether we flit among a variety of social groups or prefer closer-knit relationships.
"What it means is that your genes predict whether or not two of your friends are going to be friends with one another," Fowler said.
(Related: "Ant Study Shows Link Between Single Gene, Colony Formation" [January 24, 2002].)
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