Jean Jansem was born in 1920 at Seuleuze in Asia Minor and spent his early childhood in Salonika. When he was twelve years old his family settled in Paris.
As a schoolboy he liked to copy reproductions of ancient sculptures, then following an accident in which he broke the bones of his foot, he spent three years in hospital. Thus, at an age when most children were playing, Jansem came to know the meaning of solitude. This long period of physical inactivity accustomed him to long periods of reflection and meditation, and from this came the gravity that has always characterized him.