“Don’t hang out with those kids. They’re bad seeds.” We all can see the classic clique play out, preached by parents, teachers and family sitcoms. Then a few episodes later the innocent student is corrupted by the rough crowd, addicted to drugs and alcohol. Cliques are called cliques for a purpose, the obvious truth they hold. Recently, some researchers decided to put these cliques to the clinical test.
Examining data from over 12,000 adults, researchers found that if a person smokes, others up to three degrees of separation away from them are more likely to smoke. Meaning, if your friend has a friend that smokes, you’re more likely to smoke. To break it down further, if you smoke, it is 61% more likely that your friends smoke, 29% more likely that your friends-of-friends smoke, and 11% more likely that your friends-of-friends-of-friends smoke.
The question of what exactly causes us to be so similar to our friends cannot be answered by simple patterns of association. To help disentangle the causes of these similarities, we turn to a twin study. A study of over 800 pairs of British teenage twins revealed that the proportion of best friends a twin had who drank was about 28% heritable. The extent to which the twins’ best friends drank was also a fairly good predictor of the twins’ own drinking patterns.
By estimating the heritability of friends’ drinking patterns along with the heritability of the twins’ own drinking patterns, researchers established that this relationship was due to both overlapping genetic and environmental influences. Genetic influences on the twins’ and their friends’ drinking overlapped about 40%, while shared environmental influences (those that tend to make twins similar to one another, regardless of whether they are identical or fraternal) overlapped more than 80%.
At the end of the day this information means a lot. It tells us that the people we choose to interact with have a large affect on triggering our addictions.Equally our genetics play a large role in who we choose to surround ourselves with. Hopefully this research and nature vs. nurture gives us the awareness needed to make healthy decisions on who we keep in our company.