They found that Obama is the 13th-generation descendant of Deacon Thomas Blossom, who was born in the village of Great Shelford, Cambridgeshire, around 1580. Research by Charles Blossom, 63, and his close family had already revealed that they, too, are related to Thomas Blossom.
Experts at the New England Historical Genealogical Society traced the link between President Obama, through his white mother, Ann Dunham, to the Pilgrim forefathers. The President, who is half Kenyan and was born in Hawaii, is the 12th-generation grandchild of Thomas Blossom.
The discovery has sparked bickering between villages in Cambridgeshire about who can lay claim to President Obama's English roots.
Thomas Blossom was one of seven children of Peter and Annabel Blossom from Great Shelford, Cambs. After his birth the family moved to Stapleford in around 1582, where Peter is described as a "husbandman", or small farmer, in records.
In 1605, at the age of 25, Thomas married Anne Elsdon in Cambridge. The couple fled to the Dutch city of Leiden to escape religious persecution in England along with other exiles known as the Pilgrims. During their time there the couple buried three children who died at a young age.
They first attempted to sail to the New World in 1620 on board the Speedwell, a sister ship of the Mayflower. But while the Mayflower carried America's founding fathers across the Atlantic, the Speedwell developed a leak and had to turn back.
The original Mayflower was dismantled for scrap in 1623, but a second ship of the same name eventually took Thomas Blossom and his family to America at their second attempt in 1629.
Thomas Blossom became an important member of the Pilgrim community as the first Deacon of the Church of Plymouth, but died in 1633 from an infectious fever, probably influenza.
After his death, he left behind a daughter Elizabeth, who was nine when the family set sail, and two sons, Thomas and Peter. President Obama is descended from Elizabeth.