A new study suggests that friendships may start at a genetic level—though some scientists say it's too soon to tell.
Working at the University of California, San Diego, and singling out six genes, a team of researchers discovered that people tend to have more in common genetically with friends than non-friends.
After controlling for genetic likeness due to sex, age, race or common ancestry, friends still tended to have the same SNP at one position in a gene encoding the dopamine D2 receptor, DRD2. Friends also showed more variation at one position in a cytochrome gene, CYP2A6, than non-friends.
An 'opposites attract' phenomenon may account for the variation in CYP2A6 among friends, say the authors. The study also suggests that genetic patterns don't always show up for friends who connect through similar activities, such as running marathons or playing musical instruments.
The researchers theorize that there may be an evolutionary benefit to having friends with comparable genotypes, as it increases the odds the friend group's collective fitness will remain stable.
Other scientists say the San Diego team's miniscule, six-gene sample type invalidates the study. But James Fowler, who spearheaded the research, says his tests were the most rigorous a geneticist can run.
While they duke it out, perhaps you'll want to rethink that old saying, "You can choose your friends, but not your family."
photo (cc) via Flickr user dok1
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