In Western Europe, we often tend to explain cultural and genetic similarities primarily through Roman or post-Roman historical events. But this narrow lens overlooks a much deeper and older story.
Take France, for example. When people observe the similarities between Bretons and the Cornish, they often attribute it to High Medieval migrations of Britons to what is now Brittany. Similarly, when they notice the closeness between modern Normans and Southern English, they cite the Viking settlement of Normandy or the Norman Conquest of England.
While those events certainly played a role, they are far from the whole picture. In reality, Northern France and Southern Britain have been in continuous contact for nearly 6,000 years—long before the Roman Empire. That extended interaction alone is enough to account for much of the genetic and cultural proximity we observe today.
Recent archaeogenetic research supports this deeper connection. A study on Iron Age Gaulish groups reveals that the Durotriges of Dorset were already trading with the Armoricans of the Cotentin Peninsula (modern-day Normandy) during the Iron Age.
Origin and mobility of Iron Age Gaulish groups
I plotted the genetic samples from this study and found that Iron Age Normans already clustered with British populations, while samples from the Hauts-de-France region aligned more closely with Germanic groups. Similarly, those from the Grand Est region grouped with modern Alsatians and Southwestern Germans. These patterns confirm long-standing regional continuity.
Furthermore, we know that Britain was repopulated—or perhaps replaced up to 90% genetically—during the Bronze Age by Bell Beaker populations who crossed the Channel by boat. Seafaring has never been a barrier for populations along the Channel and North Sea. In fact, maritime navigation is an ancient skill in this region, dating back at least to the early Bronze Age.
In short, the genetic and cultural links between Northern France and Southern Britain are not just the result of medieval events—they are the legacy of thousands of years of shared history across the sea.