Siblings often follow on opposite ends of the economic divide. In a provocative new book, sociologist Dalton Conley attributes three-quarters of the differences among Americans to their families, and explains why some siblings will follow Bill Clinton’s footsteps and others the path of Bill’s luckless brother Roger. His conclusions are based on reams data and more than 150 interviews.

“Coming from a large family,” says Conley, is “a disadvantage.” Obese children will face extra hurdles, while sons and daughters of working mothers are likely to “attain jobs that are more equitable.” Family wealth matters, since wealth prevents any child “from falling too far,” but Conley dismisses birth order, and other sweeping hard-and-fast rules to explain which sibling gets ahead and which doesn’t.

On Point talks with Dalton Conley about why and how families foster sibling inequality.

Guests:

Dalton Conley, professor of sociology and public policy at New York University. He is adjunct professor of community medicine at Mount Sinai School of Medicine and a research associate at the National Bureau of Economic Research. His latest book is “The Pecking Order: Which Siblings Succeed and Why.”