Get your DNA done. If you’ve got British Isles ancestry, you’ll find Viking overstayers in your chromosomes. :^)
I've got a story about that. My brother got the DNA test done. Sure enough 1/4 came back as "Northeastern European"....Yep. That's our dad's mom who was from Germany. 5% came back "Southern European"...yep my mom's side several generations back somebody married someone from Southern Europe. We knew the remaining 75% was British Isles. He then told me we were 15% Scandinavian.
I scoffed: Scandinavian??? We don't have any ancestors from Scandinavia! Why, they were all from the British isles and.......pause..........oh!
yeah....maybe we do actually have ancestors from Scandinavia after all.......
:^)