He was born in
Kristiania as a son of barrister Christian Nicolay Brinch (1861–1946) and Anna Catharina Rolfsen (1870–1947). He was a brother of civil servant
Christian Nicolay Keyser Brinch. In 1942 he married Anna Marta Ida Elisabeth Højer, daughter of the then-Swedish ambassador to Norway. He finished his secondary education in 1928, Next to his regular military service, Brinch joined the voluntary military training organization
Leidangen, where he served as an instructor. == World War II ==