The evidence from social science is clear: people’s behavior is powerfully influenced by the actions of those who are like them. A classic study by Harvey Hornstein, Elisha Fisch, and Michael Holmes found that New York City residents were highly likely to return a lost wallet after learning that a “similar other”—another New Yorker—had first tried to do so. But evidence that a dissimilar other—a foreigner—had tried to return the wallet did not increase the likelihood that they would try. When people are trying to determine how to act, they pay attention to how others like them behave in the same situation.