From the New York Times:
Long before Lucy Mercer, Kay Summersby or Monica Lewinsky, there was Nan Britton, who scandalized a nation with stories of carnal adventures in a White House coat closet and endured a ferocious backlash for publicly claiming that she bore the love child of President Warren G. Harding.
Now nearly a century later, according to genealogists, new genetic tests confirm for the first time that Ms. Britton’s daughter, Elizabeth Ann Blaesing, was indeed Harding’s biological child. The tests have solved one of the enduring mysteries of presidential history and offer new insights into the secret life of America’s 29th president. At the least, they demonstrate how the march of technology is increasingly rewriting the nation’s history books.
The reason you probably never heard about the Harding affair is because it happened almost a hundred years ago, it was hushed up by the Harding family to the point that they went to court to suppress a biography that wrote about it, the Harding administration was embroiled in the Teapot Dome scandal, and President Harding had the good sense to die a little over two years into his term, leaving Calvin Coolidge to clean up the mess.