 Heinason was the son of Heine Havreki (1514–1576), a Norwegian priest from Bergen who emigrated to the Faroe Islands and who helped introduce the Lutheran Reformation to the Faroe Islands, and Gyri Arnbjørnsdatter, Havreki's second wife from a powerful and wealthy Norwegian clan.In his job as a priest in the Faroes, Heine Havreki traveled much by sea, to and from the islands.Magnus accompanied him on these journeys.