A groundbreaking study conducted by researchers from Yale University and the University of California, San Diego, has unveiled that close friends often share genetic similarities equivalent to those of fourth cousins. This discovery suggests that our social bonds may be influenced by our genetic makeup more than previously understood.
Published in the Proceedings of the National Academy of Sciences, the study analyzed data from the Framingham Heart Study, focusing on 1,932 individuals. Researchers compared the genetic markers of unrelated friends and strangers, finding that friends share about 1% of their genes—a level of similarity typically found among individuals with shared great-great-great-grandparents.
Interestingly, the study found that friends tend to have similar gene variants related to the sense of smell, which could influence shared preferences and environments. Conversely, they often possess differing immune system genes, potentially providing a broader range of disease resistance within social groups.
The researchers also developed a “friendship score” based on genetic similarities, which could predict friendship likelihood with a confidence comparable to genetic predictions for certain diseases. This finding supports the idea that social environments may play a role in human evolution, with friendships contributing to genetic selection pressures.
While the study primarily involved individuals of European descent, the researchers accounted for shared ancestry to isolate the effect of friendship on genetic similarity. These findings open new avenues for understanding the interplay between genetics and social relationships, suggesting that our connections may be rooted in our DNA.