He was born in Asker as a son of painter Kristofer Sinding-Larsen (1873–1948) and Margrethe Volkersen (1880–1951).
[1] In August the same year their daughter Ellen Beate was born.
[3] His family moved a lot during his childhood, but he took the examen artium in 1922 in Kristiania.
However, he started a career in journalism, and was hired as Copenhagen correspondent for Göteborgs Handels- och Sjöfartstidning in 1929.
[1] Sinding-Larsen was an active fencer, and also chaired the Norwegian Fencing Federation for some time.