Day 3(b): The social butterfly gene

On my way to becoming a science writer, I earned a master’s degree in biology. My thesis was a genetics project, and I conducted my experiments among a group of dedicated future geneticists led by an already accomplished — indeed, famous — one. Each week, we would gather for lab meetings, where we gave reports on the progress of our projects. I was not a scientist at heart; I was just doing extended research for the science stories I would write one day. I wanted to learn the language. At most of those lab meetings, I felt like a fraud.

Usually, my fellow lab rats were gracious about my presence, even welcoming. But once, in a lab meeting, someone made an off-handed comment that every single thing about anything alive was determined by its genes. The speaker didn’t expect an argument; he assumed everyone there would agree.

“No …” I interjected. “I don’t think genes can explain everything.”

In my 35 years, I’ve had few pricklier moments. All 15 or so people at the table stopped their doodling, and looked at me. After a painfully long silence, our famous professor told me I was wrong, and the progress reports moved on.

A decade after that memorable afternoon, I stand both vindicated and corrected by an exciting new body of work. When it comes to human behavior, my professor and I were each about half right.

James Fowler, a political scientist at the University of California at San Diego, is lead author on a new study suggesting that our preference for small, close knit groups of friends or wide networks is partly determined by our DNA. The study was released today by the Proceedings of the National Academy of Sciences, and I’ve written a longer story about it for National Geographic News.

“No one has ever drawn the link between genes and social networks before,” Fowler said. “It suggests a whole new field of inquiry.”

Fowler and his colleagues analyzed 1,110 twins from 142 middle and high schools and found that the social networks of identical twins are more similar than those of fraternal twins, indicating a genetic underpinning. Based on the study, genes are about 50 percent responsible for our number of friends, and have the same degree of influence on whether we introduce our friends to each other. In other words, our tendency to flit from group to group or hang with one dense circle of friends is written in our genetic code.

Fowler and his colleagues have been unearthing one study after another in the past several years that seem to challenge the notion of free will: our genes influence our social styles and our tendency to join political parties. And in turn our friends – and their friends, out to three degrees of separation – influence whether we smoke, become obese, or experience happy or sad moods.

But Fowler thinks his work will ultimately lead to a deeper level of choice. He believes he’s closing in on a feedback loop, where genes, our social networks, and our life experiences can all modify each other in producing the outcome: our behavior. Based on the social networks study, half of our preferences are genetic, but the other half fall from our life experiences – which are partly influenced by the friends we choose, he said. 

“It’s going to be a combination of your susceptibilities and your lifetime experiences,” he said. “You have control over your life experiences.”