He came from a very old Czech theatrical family of Steimar and artistic family of Kodet, he was the son of Czech actress Jiřina Steimar and sculptor Jan Kodet. After her parents divorced, her mother married Jaroslav Juhan, a car racer, but he emigrated. This had an impact on the further studies of Jiří Kodet, who was expelled from the grammar school and was not admitted to the DAMU until the second time.