However, if you go further North, to the land of the Saami (which we call Lappland), it is quite noteworthy that during the plague of the 1300s virtually NO Saami died.
Folks further down the coast, the Norse, otherwise not different from the Swedes except for their propensity to keep Irish slaves, had a 90% death rate!
It's dollars to doughnuts that this genetically guided immunity parallels the inheritance of genes for Scandinavian porphyria, and dwarfism. I'd also guess that having an extra gene set for red receptors in the eyes, and not having any blue receptors at all show up to a greater than expected degree among these same folks.
The existence of such genes (and whatever immunities or illnesses they afford) in the broader European populations would reflect Saami incursions, hand in mitten, with their Viking associates.
Then there's the appearance of the court jesters, Saami hats on their heads, happy dust in their hands, and so terribly many of them dwarves! Makes me think of Pepin the Short, the last of his line.