US Democratic presidential hopeful Sen. Barack Obama is a distant cousin of actor Brad Pitt and Hillary Clinton is related to Pitt's girlfriend Angelina Jolie, a genealogical society said Tuesday.

Researchers at the New England Historic Genealogical Society have discovered that Jolie and Clinton are ninth cousins, twice removed, while Pitt and Obama are ninth cousins, according to a genealogical study conducted over the last three years.

Clinton, who is of French-Canadian descent on her mother's side, is also related to Madonna, Celine Dion and Alanis Morissette, researchers found. Other cousins include Camilla Parker Bowles and Jack Kerouac.

Obama, the son of a white woman from Kansas and a black man from Kenya, on the other hand, shares his ancestry with six U.S. presidents, including current commander in chief, George W. Bush, and his father, George H.W. Bush.

Other far-reaching Obama relations include Gerald Ford, Lyndon Johnson, Harry S. Truman and James Madison, as well as Vice President Dick Cheney and Sir Winston Churchill.

Republican candidate John McCain's family tree proved tougher to trace, as records on his relatives were not as extensive as either Obama or Clinton's, researchers said. He is, however, found to be a sixth cousin to first lady Laura Bush.

Genealogist Christopher Child said that while the candidates often focus on pointing out differences between them, their ancestry shows they are more alike than they think.

"It shows that lots of different people can be related, people you wouldn't necessarily expect," Child said.

Child has spent the last three years tracing the candidates' genealogy, along with senior research scholar Gary Boyd Roberts, author of the 1989 book, "Ancestors of American Presidents."

The New England Historic Genealogical Society, founded in 1845, is the oldest and largest nonprofit genealogical organization in the United States.