Most people would label "selfishness" a negative trait. As Dr. Stephen Diamond writes in Psychology Today, "most of us are taught from childhood that selfishness is sinful, bad or evil." So parents reflexively encourage generous sharing, not selfish hoarding. And if a friend says to you "you're selfish!" you are unlikely to thank her for the compliment. But we're also quick to pin the "selfish" label on others but not so often on ourselves.

For instance, in 2015, a Pew Research poll revealed that 68 percent of us "say the term 'selfish' applies to the typical American." In 2014, another survey found that 71 percent of adults believe Millennials (ages 18-29) are selfish. Remarkably, the exact same percentage of Millennials, 71 percent, agreed. In an article titled "I'm O.K., You're Selfish," The New York Times Magazine reported "only 17 percent say they are overly concerned about themselves but 60 percent think that most people are overly concerned about themselves."