Aishwarya Rai and Angelina Jolie may have common ancestors. So says a group of scientists studying the genetics of eye colour.

The researchers, from the University of Copenhagen, have found that all people with eyes in a shade of blue can trace their ancestry to one person who probably lived about 10,000 years ago in the Black Sea region.

More than 99.5 per cent of people with bluish eyes who volunteered to have their DNA analysed have the same tiny mutation in the gene that determines the colour of the iris, the study said.

Professor Hans Eiberg of the university said he had analysed the DNA of about 800 such people, ranging from fair-skinned, blond Scandinavians to dark-skinned residents of Turkey and Jordan.

“All of them, apart from possibly one exception, had exactly the same DNA sequence in the region of the oca2 gene. This to me indicates very strongly that there must have been a single, common ancestor of all these people,” he said.

The study, reported in the journal Human Genetics, indicates that the mutation originated in just one person who became the ancestor of all subsequent people in the world with bluish eyes.

“From this, we can conclude that all blue-eyed individuals are linked to the same ancestor. They have all inherited the same switch at exactly the same spot in their DNA,” Eiberg was quoted as saying.