Net worth: $32.4 billion each

Age: 77 and 81

Country: US

Industry: Candy

Source of wealth: Inheritance; Mars Inc.

Siblings Jacqueline and John Mars inherited a stake in the iconic candymaker Mars Inc. when their father, Forrest Sr., died in 1999. The notoriously private trio co-own but don't actively manage the maker of M&M's and Milky Way bars, which their grandfather started in 1931 as a confectionary business in his kitchen in Tacoma, Washington.

In 2008, Mars Inc. branched out from chocolate to gum, when it acquired the Wrigley Jr. Co. for $23 billion. Since then, it's delved into pet food, buying Iams and two other brands in 2014 from Procter & Gamble for close to $2.9 billion.

Together the siblings run the Mars Foundation, which gives primarily to educational, environmental, cultural, and health-related causes. In March 2015, John Mars was made an honorary knight by Queen Elizabeth II.

Their combined net worth has risen by $2.6 billion over the last year.