Genetic testing by the company BritainsDNA has revealed that Prince William's great-great-great-great-great-grandmother, Eliza Kewark, is half-Indian, which means that Great Britain - and possibly Kate Middleton's baby -  may one day have a future king with Indian blood, ABC News reports.

Originally thought to be have been Armenian, Kewark's background was kept very quiet by the royal family, though it was known.

"Eliza Kewark was a dark-skinned native of Bombay who had lived, without benefit of matrimony, with her great-great-grandfather Theodore Forbes while he worked for the East India Company," according to the biography "The Real Diana," by Lady Colin Campbell.

Kewark served as a housekeeper for Forbes, and had a daughter with him named Katherine, who gave birth to Jane, who gave birth to Ruth, who had Frances, who then had Princess Diana, Prince William's mother.

"Unsavory as the taint of illegitimacy was, even at that distance in time, it was nothing compared with the stigma of what was then known as 'colored blood.' Had it been generally known that Ruth [Diana's great-grandmother] and her children were part-Indian, they might never have made good marriages," the biography reads. "Eliza's true race was therefore expunged from the family tree and she reemerged as an Armenian. This fiction was maintained even when Diana married the Prince of Wales."

DNA tests were done on saliva samples from Prince William's relatives, and revealed that Prince William carries Kewark's mitochondrial DNA (mtDNA), a small piece of DNA that remains largely unchanged when passed down from mother to child, according to The Times of India.  

"I was wondering if it was possible she was Indian," said Dr Jim Wilson, a genetics expert at the University of Edinburgh and chief scientist at BritainsDNA who carried out the research. "What was an Armenian doing in Bombay? That's what got me interested." 

Researchers used birth, marriage, and death records to trace two of Kewark's living direct descendants, both of whom are third cousins of Frances Shand Kydd, Princess Diana's mother, and tested their saliva. They discovered that two direct descendants had around 0.3 percent and 0.8 percent South Asian DNA, The Times Of India reports.

It's therefore very likely that Prince William's heirs will also contain a portion of Indian DNA, including perhaps his first child with Kate Middleton, due in July.

"This was independent evidence that there was Indian ancestry," Dr Wilson said. "For me, it corroborated the findings from the mtDNA. We've got two different kinds of genetic evidence that are independent from one another and they both corroborate the story. So it really seems that our future king has a little bit of Indian blood."