 He was the son of the Danish-born priest Rasmus Sundt Christensen Kjerschow (1739–1806) and his wife Benedicte Maria Pedersdatter Hersleb (born 1744).His father was a vicar in Brønnøy, who had migrated to Norway from Jutland.He was a student at Trondheim Cathedral School and earned his cand.theol.