When Mariane Thomasdatter was born on 2 January 1818, in Flade, Morsø Nørre, Thisted, Denmark, her father, Thomas Christensen Vestergaard, was 29 and her mother, Ane Marcusdatter Kortbæk, was 26. She married Jens Pedersen Sandahl on 9 November 1849. They were the parents of at least 3 sons and 5 daughters. She died on 12 January 1901, in Ljørslev, Morsø Sønder, Thisted, Denmark, at the age of 83.