You and your friends are surprisingly genetically similar, according to a study appearing in PNAS. The similarity isn't immense -- about 1%, roughly the same as between fourth cousins -- but it's significant enough to be detectedand to have evolutionary implications.
The tendency for friends to have similar genomes might result from people befriending those of similar ancestry, but the duo are confident that isn't the case. Not only did they control for the effect of population structure and ancestry, but the Framingham data is relatively homogeneous in terms of ethnicity, consisting largely of people of European descent. In addition to the overall genetic similarity between friends, there were also a few sites in the genome which usually differed between friends, a pattern that's harder to attribute to factors like demographics.
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