There's been a lot of talk during this election cycle about political dynasties—particularly, the Clintons and the Bushes. But there's another powerful family at work, albeit behind the scenes: the brothers David and Charles Koch.

Jane Mayer, investigative journalist and staff writer at the New Yorker, traces how this pair of billionaire brothers has shaped politics and particularly the rise of the Tea Party and the radical American right in her new book, "Dark Money: The Hidden History of the Billionaires Behind The Rise of the Radical American Right."

Mayer zeroes in on "dark money," or undisclosed donations from secret contributors. Since the Citizens United Supreme Court ruling in 2011, which loosened restrictions on electoral contributions, that kind of money has flooded the American system. In 2006, there was about $5 million in "dark money" in politics; by 2012 that number had ballooned to $300 million.  

Dark money has been particularly effective in shaping political action on climate change, Mayer said.

"If you look at Congress, it's going in the opposite direction on climate change than pretty much anywhere else in the world," Mayer said. "I was interested in: what is keeping it from doing anything?"

She continued: "If you follow the money...you can trace it back to these fossil fuel companies that are tying the hands of these lawmakers, and in particular, Koch Industries, which is a major, major fossil fuel company with a tremendous carbon footprint. They don't want to see alternative fuels, because their bottom line depends on fossil fuels."

Editor's Note: David Koch is a member of WGBH's board of trustees.

Jane Mayer is a staff writeratthe New Yorker and the author of "Dark Money: The Hidden History of the Billionaires Behind the Rise of the Radical American Right." To hear more from Jane Mayer, tune in above.