Here is a question that is at the core of our work at State of Opportunity: How much of your economic destiny is tied to your parents, and how much do you control?

When scientists try to answer this question, what they’re measuring is something called “social mobility.”

We've been looking into new research that suggests your fate is not just tied to your parents, but to ancestors hundreds and hundreds of years ago. And improving opportunity across generations might be a lot harder than anyone imagined.

Gregory Clark did not set out to study social mobility. He’s an economic historian at the University of California at Davis. He was trying to study how the British elite formed in the lead up to the Industrial Revolution.

So someone suggested he trace last names – surnames. There is a really long record of elite names in British society.

“For example, in England, we know the names of most people who went to Oxford and Cambridge from about 1200 right up until the present,” Clark says.

But he didn’t believe these names would tell him much about the status of families over time. A surname is just one branch in a vast family tree. And, all the previous work on social mobility suggests that the status of a name would change in three or four generations, as a family rose and then fell through the social ranks.

But it turns out, surnames told Clark a whole lot.

"If I just know that you share a rare surname with someone who was wealthy in 1800, I can predict now that you’re nine times more likely to attend Oxford or Cambridge," he says. "You’re going to live two years longer than an average person in England. You’re going to have more wealth. You’re more likely to be a doctor. You’re more likely to be an attorney.”

This finding was a big surprise. So Clark, and some fellow researchers checked results in other countries. They looked at records of elite status - top colleges, listings of doctors and lawyers. They checked how often certain names showed up in these places, compared to how common they were in the general population. Then they checked how that comparison changed over time to see how names were moving in and out of elite positions.

They checked in the United States, Sweden, South America, Japan …

"And astonishingly, there’s no more mobility in Sweden on these measures than there is in South America," Clark says. "And that America looks just like England, looks just like Sweden."

And, even more astonishingly, the numbers are the same in different time periods.

What Clark is saying is if you start from a common background, your chance of making it into the elite is the same in the United States as it is in South America. And it was the same in the Middle Ages as it is today.

"It’s almost a social constant, in the sense of a physical constant like Avogadro’s number or Planck’s constant, says Joseph Ferrie, an economic historian at Northwestern University. He’s been following Clark’s work on surnames almost from the beginning, and he says it’s been fascinating.

“It is shocking that the number is as constant as it is," Ferrie says. "But it’s hard to find any holes in the argument that he makes suggesting that this really is something that does look the same in a variety of places and times."

Clark’s method is unique among people who study social mobility. Ferrie and most other researchers look at individual families, not just family names. But both approaches have been transformed in the past few years, as more information from censuses and household surveys have become searchable online.

Until now, nearly all the research into social mobility has only been able to cover two generations. Now, it’s finally becoming possible to look at many generations, and when you do that, it looks like there’s a lot less mobility than what we thought.

"We’re kind of, I think revising our impression of how much immobility there is," says Robert Mare, professor of sociology at UCLA. "Before we thought that how well we do is dependent on our parents -we still think that - but now if it’s also dependent on our grandparents rather than random luck or one’s own achievement, then that tells us something about how sticky inequality is in our society.”

If Gregory Clark’s research turns out to be right, there’s actually a number we can put on that stickiness, no matter where you live, or when you were born.

"We can’t predict the individual aspects of where you’ll end up," he says. "But if we want to rank you overall in society, maybe as much as 60 percent of the outcome is determined at the time of conception."

And if that number is as fixed as Clark believes it is, it raises some pretty big questions about how to improve opportunity - or whether we even can.