Siblings John, Jacqueline, and the late-Forrest Mars inherited a stake in Mars, Inc. after their father died in 1999. The siblings are notoriously private, and don't actively manage the candy maker company. But they do run the Mars Foundation, which gives primarily to educational, environmental, cultural, and health-related causes.
Net worth: $33.5 billion each
Age: 82, 78
Citizenship: United States
Industry: Food and beverage
Source of wealth: Inherited; Mars Inc.