Claudia Goldin, an economics professor at Harvard University, told Stephen Dubner on the podcast "Freakanomics" what really causes the gap.
The gap is due mostly to choices men and women make in their careers and not discrimination, she said.
Goldin argued that once you account for a number of factors, including taking time off from work and different careers, then there isn't "tons of evidence that it's true discrimination."
Goldin also suggested that the old claim that men are just better at bargaining doesn't contribute much to the gap. She said studies have shown men and women show up to a job straight out of college (meaning they have the same education level) and earn the same amount.
"So if men were better bargainers, they would have been better right then. And it doesn't look as if they're better bargainers to a degree that shows up as a very large number," Goldin said.
But as men and women progress through their careers, Goldin said, the difference in pay comes to light.
"But we also see large differences in where they are, in their job titles, and a lot of that occurs a year or two after a kid is born, and it occurs for women and not for men," Goldin said. "If anything, men tend to work somewhat harder."
(via Washington Examiner)