Before we leave the Vikings here are two recent posts about the genetics and ethnic mix of those we know as Vikings.
This research, based on examination of Viking burials across a wide area, shows that these were not all Scandinavian or not entirely so. Some were apparently Pictish, others had Mediterranean or Asiatic ancestry. Being a Viking - the term means raider or voyager as I recall - was a ‘lifestyle choice’ rather than a matter of ethnicity or long-established group identity. If you felt like joining up, and presumably were accepted, well off you went raiding and pillaging, but also trading and colonising.
The MailOnline has Not all 'Vikings' were Scandinavian - some were Picts and the Guardian website has perhaps more discussion at Dark hair was common among Vikings, genetic study confirms