Or, how innate is willpower?
Back in the 1960s, Walter Mischel created a simple, but ingenious, experiment to study delayed gratification. The now famous "marshmallow test" presented a group of four and five-year-old kids from Stanford University's nursery school with a difficult challenge. They were left alone with a treat of marshmallows. They were told they could help themselves at once, or, if they waited for up to 20 minutes get two marshmallows.
Mischel, now an eighty-year-old of Columbia University, reveals that the original purpose of the test was to learn how kids delay gratification. It was not to assess how well they did. But his own children, who had attended the nursery school, told him years later about how well socially and academically their friends from the pre-school who delayed their eating were doing.
Mischel dug into their anecdotes and found--to his surprise--a number of...