In 2004, current Senate Majority Leader Mitch McConnell and his wife, current US Transportation Secretary Elaine Chao, had an average net worth of $3.1 million. Ten years later, that number had increased to somewhere between $9.2 million and $36.5 million.

One source of the windfall, according to a new book from Peter Schweizer, was a 2008 gift from Chao’s father, James Chao, for somewhere between $5 million and $25 million. But this gift could be seen as more than just a gift. It may have been acquired, according to Schweizer, thanks to the couple’s fealty to China, the source of the Chao family fortune.