Sheldon Gary Adelson is the fifth wealthiest person on our list for a reason. On August 4, 1933, he was born to Jewish parents of mixed heritage. The father is from Ukraine, while the mother is from Lithuania. Sheldon Adelson is a business entrepreneur, investor, and philanthropist. He is best known for his work with casinos and poker. In 2011, Forbes estimated his net worth at $20 billion. Sheldon's wife, Miriam Adelson, is not only her husband's partner in business but also his wife. They married in 2003 after meeting at a casino where she worked as a dealer. Before marrying Sheldon, Miriam was engaged to another wealthy businessman named Milton Friedman. They had been dating for several years but didn't marry until after he died in 1976. Their daughter, Olivia, was born in 2004. She is a student at Stanford University with an estimated net worth of $1 billion. Olivia's twin brother, Alexander, was born two months later. He too has a massive fortune thanks to his billionaire parents. His estimated net worth is $5 billion. In addition to being married to each other, Sheldon and Miriam Adelson are also business partners with another couple named Ronald and Esther Siegal. The foursome are known as the "Jewish Four Friends" and run a large casino empire in Las Vegas called Riviera Resort & Casino.