Friends are genetically similar, says study

Next time someone rejects your offer of friendship on Facebook or (god forbid), IRL, don’t feel too bad: it might not be your looks or personality they found offensive, but your genome.

A new US study claims that friends are more genetically similar than strangers. Researchers looked at tissue samples of around 2000 people from a small town and found that friends were slightly more likely than strangers to share genetic material. Their research was published this week in the journal PNAS.

Professor James Fowler from the University of California, San Diego and Professor Nicholas Christakis from Yale University analysed participants’ samples according to nearly 500,000 markers from across the genome and discovered that people who were friends shared an average of 0.1% more DNA than strangers. Yes, that’s not a huge amount, but it is around the same as fourth cousins. (The scientists say they ruled out the possibility of people being friends and fourth cousins.)

However, other scientists are unconvinced by the research, suggesting that the fact that people from similar ethnic backgrounds have immigrated to the same small area could account for the genetic similarity. Many participants could be distantly related without even realising it. Plus, one sample from each person might not provide enough information about their DNA, according to Professor Evan Charney from Duke University, who told the BBC, ‘People do not have the same genome in all the cells and tissues of their body.’

Replicating the study’s results using multiple DNA samples taken from a more diverse population would clearly add weight to its conclusions, but the authors stand behind their research. Professor Christakis said, ‘We are somehow, among a myriad of possibilities, managing to select as friends the people who resemble our kin.’

As much as your best friend might feel like a sister or brother to you, they’re not. But they could be just like a fourth cousin.

Image via Marion Doss’s Flickr.