A study from a controversial pair of US researchers claims that we are more genetically similar to our friends than we are to strangers.
Looking at differences between nearly 2,000 people, recruited as part of a heart study in a small US town, they found that friends shared about 0.1% more DNA, on average, than strangers.
While small, this is the same level of similarity expected for fourth cousins.
Other scientists are sceptical about the paper, which was published in PNAS.
“I think that they’re unusual findings, and that usually draws criticisms from scientists,” said Prof James Fowler, one of the study’s authors and a professor of both medical genetics and political science at the University of California, San Diego.
Together with Prof Nicholas Christakis from Yale University, Prof Fowler analysed nearly 500,000 single-letter markers from across the genome.
These results were useful because as well as providing DNA samples, participants were asked who their closest friends were. “Because the study started in a small community, many people that were named as friends, also happened to be involved in the study,” Prof Fowler explained.
