Nos. 9, 10, 11, and 12: Dannine Avara, Scott Duncan, Milane Duncan Frantz, Randa Duncan Williams
Dannine Avara (49, Houston): $5.5 billionScott Duncan (30, Houston): $5.5 billionMilane Duncan Frantz (42, Houston): $5.5 billionRanda Duncan Williams (52, Houston): $5.5 billion
The four children of Dan L. Duncan found themselves thrust onto this list after their father died of a cerebral hemorrhage, in 2010. Duncan, who was the richest man in Houston at the time of his death, was born poor in the East Texas hamlet of Center. He experienced tragedy at age seven, when his brother died of blood poisoning and his mother died of tuberculosis; as a teenager he followed his father’s example and went to work as a roughneck. Later he became an accountant for Wanda Petroleum. Having learned the oil business from the ground up, in 1968 he founded Enterprise Products Partners with a truck and $10,000. Soft-spoken and unassuming, Duncan saw opportunity in the sleepy sidelines of oil transportation: he began to buy up pipeline networks—which were expensive to build and maintain—from large oil companies, who happily paid him a fee for moving their product. His decision was prescient and profitable: in 1998 Enterprise went public, and today it operates some 50,000 miles of pipeline as well as storage facilities and marine transport. An avid game hunter, Duncan was also a committed philanthropist, giving hundreds of millions to Houston-area hospitals, including $100 million toward the creation of a cancer center at Baylor College of Medicine. He was also the first American billionaire to pay no estate tax: the law lapsed in 2010, the year he died, because of a legislative loophole. And so Duncan’s children inherited billions that might otherwise have gone to the government. Like their father, they keep a low profile, drawing scant attention even in Houston’s society pages. In February Randa, the oldest, was named nonexecutive chairman of Enterprise GP Holdings, where she has served on the board since her father’s death. A former practicing attorney, she is also on the boards of the Houston Zoo, the Houston Museum of Natural Science, and the Manned Space Flight Education Foundation. Earlier this year Dannine was identified as a target of a California con man’s extortion scheme; Milane serves on the board of the Hermann Park Conservancy. Meanwhile, Scott, at age thirty, is the country’s youngest billionaire not connected to a social media company.