I've written extensively on how the gender wage gap would be more accurately referred to as the "gender earnings gap," because the gap is due mostly to choices women make and not discrimination.

But now you don't have to take my word for it, you can listen to Claudia Goldin, an economics professor at Harvard University. Goldin spoke to Stephen Dubner, the journalist behind the popular podcast "Freakanomics," in a segment about what really causes the gap.

As one can imagine, Goldin comes to the same conclusion that I and many others have: That the gap is due mostly to choices men and women make in their careers and not discrimination.

"Does that mean that women are receiving lower pay for equal work?" Goldin asked after listening to clips of President Obama and comedienne Sarah Silverman claim that women earn 77 cents to the dollar that men earn. "That is possibly the case in certain places, but by and large it's not that, it's something else."

That "something else," is choice — in the careers that women take, the hours they work and the time off they take. Dubner asked her about evidence that discrimination plays a role in the gap, to which Goldin responded that such a "smoking gun" no longer exists.

"It's hard to find the smoking guns, OK? The smoking guns existed in the past," Goldin said. "I have found many a smoking gun where you find actual evidence of firms saying, for example, 'I do not hire Negroes.' Or, 'I do not hire women.' I mean, you actually find these in 1939."

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."

I can see her last sentence there gaining the ire of many a feminist. Of course women work hard, Goldin isn't suggesting they don't work hard — she's referring to the difference in the number of hours women and men work.

"And I know that there are many who have done many experiments on the fact that women don't necessarily like competition as much as men do — they value temporal flexibility, men value income growth – that there are various differences," she added.

When it comes to taking time off for children, Goldin said that was a "large factor" because "anything that leads you to want to have more time is going to be a large factor."

Goldin pointed out that among similar occupational groups — like health care — women earn less than men, but it is because of "a host of reasons, one of which is that they're not working the same amount of time."

Women, she said, are opting for more flexible hours, and jobs that allow for such flexibility also pay less. An example she gave was the difference between a high-paying job at a big law firm and a corporate counsel. The big law firm may pay more, but would also require round-the-clock availability, long hours and travel, whereas the corporate counsel would pay less but provide more stability in hours.

And for all the complaints that it's "society" that forces women to take time off, that same "society" stigmatizes men who do and force men to earn more once a child is born. "Stay-at-home-dads" often conjure up images of unsuccessful beta males. Maybe if there weren't such a stigma surrounding fathers who want to take time off of work to care for their children while mothers pursue their career, the gap wouldn't exist or would even be reversed.

But the bottom line is that the "gender wage gap" is not caused by discrimination, and therefore cannot be fixed through government action to reduce discrimination. It can only be fixed by forcing women to make different choices, which is absurd.

Ashe Schow is a commentary writer for the Washington Examiner.