The age old rivalry between Cornwall and Devon has been highlighted by DNA research showing that even today the populations are two distinct groups divided by the Tamar, and more controversally shows that despite its 'celtic' connections, people in Cornwall are closer in make up to their English cousins than any of the other celtic nations.

The genetic map of the British Isles shows that inhabitants of Cornwall and Devon are divided by more than the river border, with Cornish genes on one side and distinct and different Devon DNA on the other.

The study also showed that the Cornish have fewer genes in common with the rest of the UK than the people of Devon and that despite their claims to a cultural kinship, the Celtic peoples do not form a single group.

The Cornish have DNA that is much more similar to that of other English groups than to the Welsh or the Scots.

Scotland, Northern Ireland, Wales and Cornwall all have a very different genetic make-up.

The study has also shown that in England, particularly in the east and south many people have 25 per cent German DNA and a large amount of French DNA.

Oxford University geneticist Professor Peter Donnelly said: "One might have expected those groups to be quite similar genetically because they were Celtic. But while see distinct groups in those regions they are amongst the most different.’

Archaeologist Professor Mark Robinson said: "I had assumed that there was going to be this uniform Celtic fringe extending from Cornwall through to Wales into Scotland. And this has very definitely not been the case."

An international team, led by researchers from the University of Oxford, UCL (University College London) and the Murdoch Childrens Research Institute in Australia, used DNA samples collected from more than 2,000 people to create the first fine-scale genetic map of any country in the world.

Their findings, published in Nature, show that prior to the mass migrations of the 20th century there was a striking pattern of rich but subtle genetic variation across the UK, with distinct groups of genetically similar individuals clustered together geographically.

By comparing this information with DNA samples from over 6,000 Europeans, the team was also able to identify clear traces of the population movements into the UK over the past 10,000 years. Their work confirmed, and in many cases shed further light on, known historical migration patterns.

Dr Michael Dunn, Head of Genetics & Molecular Sciences at the Wellcome Trust, said: “These researchers have been able to use modern genetic techniques to provide answers to the centuries-old question - where we come from. Beyond the fascinating insights into our history, this information could prove very useful from a health perspective, as building a picture of population genetics at this scale may in future help us to design better genetic studies to investigate disease.”  

Leslie S et al. The fine-scale genetic structure of the British population. Nature 2015.