Friends have more DNA in common than strangers


 (MJTH |

People may unsuspectingly choose friends who have some DNA sequences in common with them, a new analysis finds.


The study lends a possible scientific backing for the well-worn clichs, "We're just like family," or "Friends are the family you choose," the researchers said.








The findings suggest that choosing friends who share similar genes is a behavior that may have contributed to human evolution, the researchers said.

"Imagine you're the first person on the planet to evolve the capacity to speak," Christakis told Live Science. "Do you think that mutation would increase your Darwinian evolution? No. Because you would have no one to speak to."

The usefulness of a speech gene would depend on whether a friend shared the same gene, Christakis said. In other words, there's an advantage to people's genes evolving in relation to those of their friends.

The researchers acknowledged some caveats to their conclusions. For example, it may be that people form friendships with those of the same ethnicities, they said. But to take this into account, the researchers studied participants from a homogenous group of people, from a Caucasian background.

The researchers compared pairs of strangers within this population as well as friends, using a "friendship score," which predicts whether two people could be friends based on their genetic background.

"What we're reporting is the difference between people who are friends, and people who could be friends, all from the same ancestry," said study researcher James Fowler, a professor of medical genetics at the University of California, San Diego.

The study was published July 14 in the journal Proceedings of the National Academy of Sciences.
