Modern Scandinavians carry older ancestry from continental Europe, the British Isles, and the Eurasian Steppe. In our ancient-only comparison, those layers show up as non-Nordic — so even someone with deep Scandinavian roots won't hit 100%.
Why isn't my Nordic Index 100% if my family is Scandinavian?
Why a fully Scandinavian family won't necessarily show a 100% Nordic Index.