“Friends are the family you choose for yourself,” the old saying goes, but new research indicates that your close friends may be more like your family than you realize.
A study published this week in the Proceedings of the National Academy of Sciences looked at 1,367 pairs of close friends from Framingham, Massachusetts, who had been friends since the 1970’s. Researchers compared the participants’ DNA to one another, and then to the DNA of approximately 1.2 million pairs of strangers. In their research, scientists from Yale and the University of California at San Diego looked at well over 400,000 points of comparison along the DNA strands of each of the participants in the study.
Surprisingly, the study revealed that close friends tend to be more genetically similar to each other than they are to strangers, including strangers with whom they share the same ethnic background. In fact, the average genetic similarity among close friends was equivalent to the level of genetic kinship that exists between fourth cousins, i.e. people who share a set of great-great-great-grandparents. That’s a pretty distant familial relationship, obviously, but still statistically significant enough that scientists are baffled as to why good friends could be so genetically similar without technically being related.
One explanation may be that people with similar genetic makeup tend to live in or move to similar environments, increasing the chances of their meeting and becoming friends. It may also be that people with similar genetic traits also tend to share similar skills, making it more likely that they will find themselves engaged in the same type of work or activity. Interestingly, the study revealed that close friends tend to share a closer sense of smell than any of the other senses.
A possible implication from the study, if the results are eventually shown not to be specific to the good people of Framingham, is that you might be able to create and take a genetic test, to determine whether you and someone else should become friends. At first glance this might seem to be a pointless test, since even genetic similarity does not guarantee the bonds of friendship. After all, almost everyone has at least one genetically close relative whom they do not get along with or do not speak to, for various reasons.
However, if these findings hold up over time, there could be potential practical implications beyond scientific theory. For example, one could imagine that, in the formation of sports teams or military units, such a genetic test for similarity could be viewed as increasing the statistical chances of the members of the group being able to work well together. Although not a guarantor of success, genetic closeness could be one factor among many to be taken into consideration, in the formation of productive groups.
Admittedly, most of us don’t need a test to tell us whom we care about the most. By its very nature, true friendship doesn’t require a scientific explanation: it’s simply a gift, one freely given, received, and reciprocated. Yet at the same time, it’s still interesting to learn that those people in your life whom you love as much as your own family may, in a sense, be just like family, on a genetic level.