Can you count your friends on one hand? Or are you constantly double-booked? The answer is likely to lie in your genes, according to a new study, “Model of genetic variation in human social networks”, published in the Proceedings of the National Academy of Sciences USA.

Researchers at Harvard Medical School, led by Nicholas Christakis, found that “popularity is influenced by our genes, meaning some people are natural-born party animals, while others are more likely to lurk on the margins at social gatherings.” (The Guardian 26 Jan 2009). The study looked at “more than 1,000 adolescents who were either identical twins or fraternal twins. By comparing information on the number and closeness of their friendships, they established that social networks were more similar among identical twins.” (The Guardian 26 Jan 2009).

But there is more to it than your genes just making you more popular; your genetic make-up might also influence the shape of your social network and your position within it: “[...] how interconnected your friends are depends on your genes. Some people have four friends who know each other and some people have four friends who don't know each other.” (Reuters UK 26 Jan 2009).

So why is your position in a social group heritable? There might be an evolutionary explanation: “[...] there were times in human development when it was more important to be at the centre of a group, for instance when food was scarce, and times when it was better to be on the fringes of a society, such as when disease was rampant.” (The Telegraph 27 Jan 2009). The balance of these two factors could explain why both traits are still present: “Because both strategies have advantages over the other, it is possible both survived in our genes” (The Daily Mail 27 Jan 2009).