Picture a viking - chances are it's a blonde-haired, fair-skinned warrior with a twin-horned helmet.
They might even be getting ready to board a longship with other Vikings from across Scandinavia, excited for a summer of pillaging coastal settlements across northern Europe.
While it makes for good TV and comic strip fodder, new research suggests little of it's true.
"The history books will need to be updated," said Eske Willerslev, director of The Lundbeck Foundation GeoGenetics Centre, University of Copenhagen.
"We have this image of well-connected Vikings mixing with each other, trading and going on raiding parties to fight kings across Europe because this is what we see on television and read in books - but genetically we have shown for the first time that it wasn't that kind of world."
Prof Willerslev's team spent six years looking at DNA sequenced from the remains of 442 Viking skeletons found across Europe. All of them died in the 'Viking Age' - between 800 and 1066, when Scandinavian tribes conquered and settled across Europe, and even reached North America.
But it turns out much of what we believe about them simply isn't true. Firstly, many didn't all have blonde hair.
"We found that Vikings weren't just Scandinavians in their genetic ancestry, as we analysed genetic influences in their DNA from southern Europe and Asia which has never been contemplated before," said Prof Willerslev.
"Many Vikings have high levels of non-Scandinavian ancestry, both within and outside Scandinavia, which suggest ongoing gene flow across Europe... No one could have predicted these significant gene flows into Scandinavia from southern Europe and Asia happened before and during the Viking Age."
Secondly, their raiding parties weren't massive efforts organised by a central authority - many appeared to be family affairs. One burial site in Estonia housed four Viking brothers who died on the same day - perhaps in a raid gone wrong.
"The rest of the occupants of the boat were genetically similar, suggesting that they all likely came from a small town or village somewhere in Sweden," said Ashot Margaryan, genetics professor at the University of Copenhagen.
Other 'Viking' burial sites contained skeletons with no Scandinavian DNA at all.
"Individuals with two genetically British parents who had Viking burials were found in Orkney and Norway," in northern Scotland said University of Bristol's Daniel Lawson, who contributed to the study.
"This is a different side of the cultural relationship from Viking raiding and pillaging."
In other words, the Vikings didn't always spread their culture and influence through violence and intimidation - some outside Scandinavia appear to have chosen to become Vikings.
A thousand years later, the research shows 6 percent of Britons have Viking DNA - not too far behind Sweden's 10 percent.
"We didn't know genetically what they actually looked like until now," said Prof Willerslev. "We found genetic differences between different Viking populations within Scandinavia which shows Viking groups in the region were far more isolated than previously believed.
"Our research even debunks the modern image of Vikings with blonde hair as many had brown hair and were influenced by genetic influx from the outside of Scandinavia."
As for the horned helmet, famously worn in operas and by cartoon Viking Hagar the Horrible, they were a 19th century invention. The only complete Viking helmet ever found intact has no horn.
The research was published in Nature.
