An interesting paper in PNAS by Nicholas Christakis and James H. Fowler claims that our friends are more closely related to us than random strangers. On average, we are related to our friends at a level close to that of fourth cousins. Maybe people have to go that far from their family before they can stand being around them without being forced to.
Beyond just the average similarities across the whole genome, they find that friends tend to be most similar in affecting the sense of smell, and most dissimilar in genes controlling immunity. The immunity one makes sense in that it would be good to hang around with people who are not susceptible to the same kinds of infections as you are.
Another fascinating result from the study is that genes that are more similar between friends seem to be evolving faster than other genes. This could also explain why humans evolution seems to have speeded up over the last 30,000 years. The authors suggest that the social environment is a force in driving the evolution of humans.
The authors use the Framingham Heart Study dataset to draw their conclusions which comprises of a relatively homogeneous population of European ancestry. It would be interesting to see whether these results hold up in other populations. Among other interesting results that the authors have claimed is that obesity is contagious.
Maybe this explains why certain people just click as friends even though you have extremely dissimilar tastes and temperaments and some people just don’t despite all usual indicators favoring a pairing. With the FDA ordering companies like 23andme from marketing health related results from its genetic tests, they could now use the troves of data they have collected to not just tell you your potential ancestry and present relatives, but also suggest new friends. Someday you may be able to type in ‘suggest a friend’ into the searchbar and hit I’m feeling lucky and get a match genetically guaranteed to be better than the average stranger. India, of course, is no laggard here. Genomepatri is already available and all they have to do is tie up with a marriage portal and along with all the other data that goes into find an ideal match, you could also be guaranteed to find someone who is not just a spouse but a friend. I, for one, welcome the new GATTACA world.