Though not biologically related， friends are as “related” as fourth cousins， sharing about 1% of genes. That is 1a study， published from the University of California and Yale University in the Proceedings of the National Academy of Sciences， has 2 .The study is a genome-wide analysis conducted 31，932 unique subjects which 4pairs of unrelated friends and unrelated strangers. The same people were used in both 5.While 1% may seem 6，it is not so to a geneticist. As James Fowler， professor of medical genetics at UC San Diego， says， “Most people do not even7their fourth cousins but somehow manage to select as friends the people who8our kin.”The study9found that the genes for smell were something shared in friends but not genes for immunity .Why this similarity exists in smell genes is difficult to explain， for now， 10as the team suggests， it draws us to similar environments but there is more11it. There could be many mechanisms working together that 12us in choosing genetically similar friends13“functional Kinship” of being friends with14!One of the remarkable findings of the study was the similar genes seem to be evolution15than other genes Studying this could help16why human evolution picked pace in the last 30，000 years， with social environment being a major17factor.The findings do not simply explain people‘s18to befriend those of similar19backgrounds， say the researchers. Though all the subjects were drawn from a population of European extraction， care was taken to20that all subjects， friends and strangers， were taken from the same population.