“Vikings are, genetically, not purely Scandinavian,”
“Being a Viking is not a pure ethnic phenomenon, it is a lifestyle that you can adopt whether you are non-Scandinavian or Scandinavian,” said , Prof Eske Willerslev, a co-author of the research from the University of Cambridge and the University of Copenhagen, adding that genetic influences from abroad both before and during the Viking age might help explain why genetic variants for dark hair were relatively common among Vikings.
Dr Steve Ashby, an expert in Viking-age archaeology from the University of York said the study confirmed “The evidence for gene flow with southern Europe and Asia is striking…”
While some were born Vikings, others adopted the culture – or perhaps had it thrust upon them.
https://www.theguardian.com/science/2020/sep/16/dark-hair-was-common-among-vikings-genetic-study-confirms