MONDAY, Jan. 26 (HealthDay News) -- Tucked away in the twisted strands of DNA that make you human are genes that may determine whether you are sociable or shy.

A new study comparing the two types of twins shows that genetics might affect social behavior, and the scientists who made the discovery say they are closing in on some of those "personality" genes.

"Absolutely, and we're on the case," said James H. Fowler, an associate professor of political science at the University of California, San Diego, and lead author of a report in this week's issue of the Proceedings of the National Academy of Sciences. "We've identified some, and we're waiting for further tests for verification."

"I'd rather not discuss it just yet, but we're working on it very actively," said study co-author Dr. Nicholas A. Christakis, a professor of sociology and medical sociology at Harvard University.

The new insights won't help turn a wallflower to a social butterfly, Fowler cautioned, in part because "genetic engineering is very difficult," but mostly because social behavior stems from the interplay of genetics and upbringing.

Fowler and Christakis have done several studies on social networking, showing for example that traits such as happiness and obesity can spread through person-to-person contacts.

Their latest study looked at national data on the social networks of 1,100 twins, some identical and others fraternal. They found greater similarity between the social networks of identical twins, who share the exact same genes, than those of fraternal twins, whose genes might vary slightly.

That finding is revolutionary, Fowler said. "There has been a simple model for the metabolic, neural and Internet networks, and the same model is applied to human beings -- that all parts of the network are identical and interchangeable," he noted.

That assumption can no longer be made about human social network interactions, Fowler said: "There are inherent characteristics that govern where we [as individuals] gravitate to in the social network."