 Genetic studies show that Shetlanders have almost identical proportions of Scandinavian matrilineal and patrilineal ancestry, suggesting that the islands were settled by both men and women in equal measure.The pagan reaction hypothesis proposed by Bjorn Mhyre suggests a long tradition of mobility amongst the various populations of the North Atlantic seaboard and that the expansion of Christian missions resulted in ethnic tensions that led to or exacerbated Viking expansion.There is some evidence of such mobility, such as Irish missionary activities in Iceland and Faroe Islands in the 8th century, but little that is conclusive.