"People have studied thousands of ancestral genomes and there's hardly any evidence for societies in the past of cousin-cousin marriage. From a historical perspective this really is outstanding," he added.

Stockhammer and his colleagues believe such unions were down to economics, to prevent family land from being divided.

He explained: "All of the driving force is to unite the land within the family. If you look at what people were growing, it was grapes and also olives for olive oil, but both grapes and olives might need to be at a certain place for decades.

"If you marry in your family it means that you focus on staying in the same area."

He said that, by contrast, in other parts of Bronze Age Europe, women often traveled hundreds of miles in order to marry. Resources in those areas would have been more plentiful, he explained.