This is the rare study I'd be really interested to see repeated with college students.
The population used in this study was the population in the Framingham Heart Study, presumably because they had the DNA and friendship graph already lying around. But starting from a small town's population, you've got pre-existing social networks which will both influence the future genetics and the future social networks of the town. You could get a lot of confounding correlations like "you're more likely to be friends with someone you live nearby to and you're more likely to live nearby to people you are related to".
If you repeated this with college students you'd have friendships formed between people with few if any previous connections.
The population used in this study was the population in the Framingham Heart Study, presumably because they had the DNA and friendship graph already lying around. But starting from a small town's population, you've got pre-existing social networks which will both influence the future genetics and the future social networks of the town. You could get a lot of confounding correlations like "you're more likely to be friends with someone you live nearby to and you're more likely to live nearby to people you are related to".
If you repeated this with college students you'd have friendships formed between people with few if any previous connections.