Science and Tech


Genetically, Close Friends Are Like Distant Cousins

A new study says people tend to make friends with those who are genetically more like ourselves.
Posted at 8:30 PM, Jul 14, 2014

Best friends — you grow close to those special people in your life by sharing emotions with them, going through tough times with them and much more. But did you know you might be somewhat related to them, too? (Via Getty Images)

A new study from authors at Yale and the University of California San Diego says we share a bit of DNA with our close friends. The study claims close friends share 1 percent of their genetic makeup. That's about the same similarity as fourth cousins — or those who have the same great, great, great grandparents.

The study, published in Proceedings of the National Academy of Sciences, looked at 1,932 people and compared 1.5 million genetic markers.

Study co-author Professor James Fowler, told KPBS

"We were really interested in how social networks evolved, how we make friends, where did all this come from. We were really interested in this evolutionary tendency for us to choose friends who are like us."

But why should DNA factor into our choice of friends? USA Today writes, "The researchers also can only speculate about why evolution might favor friends with more genes in common. When friends help friends, perhaps more survive to pass those genes along."

Researchers also found friends are most similar in genes related to our sense of smell. (Via Getty Images

Fowler and co-author Nicholas Christakis have studied genes and social networking for a while, publishing a similar study last year. Christakis also gave a TED Talk in 2010 about how certain social traits can be shared across groups of friends.

Christakis also gave a TED Talk in 2010 about how certain social traits can be shared across unrelated groups of people.

"I think understanding social networks and how they form and operate can help us understand not just health and emotions, but all kinds of other phenomena like crime, warfare and economic phenomena." 

So if you have friends who are like family, that's a closer to the truth than you might have thought.