Dr. Jim Wilson, a geneticist at the University of Edinburgh in Scotland and chief scientist at BritainsDNA, said the prince's great, great, great, great, great grandmother, Eliza Kewark, was of Indian origin.
BritainsDNA conducted testing on DNA samples from two of Kewark's living descendants, Britain's The Independent reported Friday.
The tests found the descendants -- third cousins of Princess Diana's mother, Frances Shand Kydd -- share the same mitochondrial DNA as Prince William. Mitochondrial DNA is DNA passed down mostly unchanged through the maternal lineage, the newspaper said.
Kewark's mitochondrial DNA was extremely rare, scientists discovered, and has only been found in 14 other people, 13 in India and one in Nepal.
Kewark was the housekeeper for Prince William's fifth great grandfather, Theodore Forbes while he lived in Surat in East India. She gave birth to two children, Katherine and Alexander, The Independent said.
Both the children were sent back to Britain where Katherine later married a British man, James Crombie.
There are no plans at this time for Prince William to travel to India to connect with his distant relations, The Independent reported.
"It's a great thing to unite people across the distances," Wilson said. "It shows commonality."