Finn was one of the eight children, seven brothers and a sister, of Árni Arnmódsson or Armódsson, a lendmann, and his wife Þora Þorsteinsdóttir (daughter of Thorstein Gallows).
Finn was part of a large family with seven brothers and one sister, which included their parents, Árni Arnmódsson or Armódsson, a lendmann, and his wife Þora Þorsteinsdóttir (daughter of Thorstein Gallows).