Culture is never all-determining. Individuals can defy the most dominant culture and write their own scripts, as Mr. Combs himself did. They can create narratives of pride that reject the master narratives of their society, or turn those narratives around. In any given family, an unusually strong parent, grandparent or even teacher can instill in children every one of the three crucial traits. It’s just much harder when you have to do it on your own, when you can’t draw on the cultural resources of a broader community, when you don’t have role models or peer pressure on your side, and instead are bombarded daily with negative images of your group in the media.

But it would be ridiculous to suggest that the lack of an effective group superiority complex was the cause of disproportionate African-American poverty. The true causes barely require repeating: They include slavery, systematic discrimination, schools that fail to teach, employers who won’t promote, single motherhood and the fact that roughly a third of young black men in this country are in jail, awaiting trial or on probation or parole. Nor does the lack of a group superiority narrative prevent any given individual African-American from succeeding. It simply creates an additional psychological and cultural hurdle that America’s most successful groups don’t have to overcome.

At the same time, if members of a group learn not to trust the system, if they don’t think people like them can really make it, they will have little incentive to engage in impulse control. Researchers at the University of Rochester recently reran the famous marshmallow test with a new spin. Children initially subjected to a broken promise — adults promised them a new art set to play with, but never delivered — almost invariably “failed” the test (snatching the first marshmallow instead of waiting 15 minutes for a promised second). By contrast, when the adults followed through on their promise, most kids passed the test.

The same factors that cause poverty — discrimination, prejudice, shrinking opportunity — can sap from a group the cultural forces that propel success. Once that happens, poverty becomes more entrenched. In these circumstances, it takes much more grit, more drive and perhaps a more exceptional individual to break out.

Of course a person born with the proverbial silver spoon can grow up to be wealthy without hard work, insecurity or discipline (although to the extent a group passes on its wealth that way, it’s likely to be headed for decline). In a society with increasing class rigidity, parental wealth obviously contributes to the success of the next generation.

But one reason groups with the cultural package we’ve described have such an advantage in the United States today lies in the very same factors that are shrinking opportunity for so many of America’s poor. Disappearing blue-collar jobs and greater returns to increasingly competitive higher education give a tremendous edge to groups that disproportionately produce individuals driven, especially at a young age, to excel and to sacrifice present satisfactions for long-term gains.

THE good news is that it’s not some magic gene generating these groups’ disproportionate success. Nor is it some 5,000-year-old “education culture” that only they have access to. Instead their success is significantly propelled by three simple qualities open to anyone.