Obama, Romney Family Trees Hold Slaves, British Country Folk America's first black president likely descended from the first U.S. slave.

July 30, 2012 -- The United States' first African-American president is likely a descendent of the first documented enslaved African in colonial America, researchers at Ancestry.com said today.

"I don't even know the words to describe it," Anastasia Harman, the lead family historian for Provo, Utah-based Ancestry.com, said. "It's amazing. It's seemingly unbelievable, but the research strongly suggests that this is the only possibility."

President Obama is the 11th great-grandson of John Punch, a black man who came to America in the 1600s as an indentured servant and was enslaved for life in 1640 after trying to escape his servitude, according to a two-year Ancestry.com study of thousands of records from colonial Virginia.

Although Obama's father was a black man from Kenya, his ties to slavery stem instead from his white mother, Stanley Ann Dunham, Harman said. The enslaved, black Punch had children with a free white woman. Because their mother was free, Punch's mixed-race kids were born free and went on to become "prominent" land owners in Virginia, Harman said.

The Ancestry.com historian said Obama's family tree is one of the "most fascinating" on which she has ever worked because it is "dynamic" and stretches across at least three continents.

While few records remain about Obama's father's side of the family, his mother's side ranges "from prominent land owners to people fleeing the Irish potato famine to indentured servants," Harman said.

Obama's Republican rival Mitt Romney, on the other hand, can trace the majority of his family tree to one country: England. His great-great grandfather, Miles Romney, was a carpenter from Preston, England, where he and his wife, Elizabeth, were converted by Mormon missionaries and then came to the United States in the early 1800s.

Mitt Romney's wife, Ann, can also trace her family tree back to the United Kingdom. Her grandfather was a coalminer from Wales.

In an interview last week in London, CNN's Piers Morgan asked Romney whether his U.K. ancestry made him "feel partly English?"

"Well, I'm married to a girl from Wales," Romney said. "And I'm a guy from Great Britain so I'm -- I feel like this is home, too, I guess."

After his family line hopped the pond to America, Romney's great-grandfather, Miles Park Romney, became the first of Romney's ancestors to practice polygamy, having four wives and 30 children.

Obama also has polygamy in his family history. His dad, Barack Obama Sr., descended from the Luo tribe in Kenya where polygamy was common. Obama's grandfather had at least four wives and his great-grandfather had five, the Washington Post's David Maraniss reported.

But while polygamy persists in both presidential contenders' pasts, Harman said, only Obama's ancestors have yet been traced back to slavery. Besides his tie to the enslaved Punch, Obama's family tree included slave owners, as well.

Obama's great-great-great-great grandfather George Washington Overall owned two slaves, a Baltimore Sun study found, based on 1850 census records.

First lady Michelle Obama also has slaves in her ancestry. Her great-great-great-grandmother Melvinia was a slave on a 200-acre farm in South Carolina that grew wheat, cotton and corn, according to a study first published by the New York Times.

Melvinia had a son with a white man in Georgia after being sold to his farm. That son grew up free and was Michelle Obama's great-great grandfather.