In his State of the Union address, Obama got a standing ovation for pointing to John Boehner as proof that the American Dream is intact. But Boehner’s rise from son of a barkeep to Speaker of the House might not have anything to do with modern America or its social policies. Geoffrey Chaucer was the son of shoemakers and Charles Dickens left school at age nine, as economic historian Gregory Clark notes in his forthcoming book, The Son Also Rises: Surnames and the History of Social Mobility.

Clark uses historical records to track surnames and social status over generations, and finds that rates of social mobility are surprisingly similar—and surprisingly slow— across societies as diverse as feudal England, modern Sweden and Qing Dynasty China. Most social scientists estimate that it takes about three to five generations for a family’s wealth or poverty to dissipate, but Clark says it takes a staggering ten to fifteen generations—300 to 450 years—and there’s not much the government can do about it. According to his calculations, if you live in England and share a last name with a Norman conqueror listed in the Domesday book of 1086—think Sinclair, Percy, Beauchamp—you have a 25 percent higher chance of matriculating at Oxford or Cambridge. If you’re an American with an ancestor who graduated from an Ivy League college between 1650 and 1850, it’s twice as likely that you’re listed in the American Medical Association’s Directory of Physicians.

Alice Robb: I imagine a lot of people won’t be so excited about your findings.

Gregory Clark: I realized when I was writing this book, that some people would be very uncomfortable or very unhappy with it. There are some things here that are more speculative and absolutely, people will disagree. It’s good to have robust debate. That’s our job in trying to think about the world.

I know there will be a torrent of abuse, potentially, from certain corners, because when people find things uncomfortable, they tend to attack the messenger. I’m not worried about that. I worry about making errors, getting things wrong. The rest you can’t control. I'm not going to get upset because someone says I’m justifying the class system. I’m not a policy-maker. I’m interested in the nature of society and what controls society. I'm not running for office.