Most Europeans share at least one common ancestor as recently as 1,000 years ago, a new study says.

The finding by American researchers has bolstered the claim that far from being separate ethnicities, Europeans are one big family.

"It's actually pretty intuitive. A thousand years ago is approximately 30 generations," said study author Peter Ralph, according to US News and World Report.

"Everyone has two parents, four grandparents and so on. Taken 30 generations back, that's more than a trillion ancestors, which is more than the total population of the time."

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Researchers at the University of California, Davis, found using DNA samples that most Europeans were genetically linked.

The study used 2,250 European DNA samples given from all over the continent.

They found that geographically closer people did indeed have more common ancestors, but even those thousands of miles away could find common relatives in the Middle Ages or later.

There were some surprising results, however.

Despite their penchant for great cheese and wine (and despite Roman conquests), Italians and Spaniards are genetically far apart.

Italians in fact, were rather unique in how genetically isolated they were. For many Italian DNA samples, researchers had to look 2,000 years back to find matches elsewhere.

The researchers speculate that the country's relatively isolated position – hemmed in by the sea and the Alps – kept its inhabitants genetically more "pure."

The study was published in PLoS One.