Oscar and Alphonse had British nationality; Adele French, and they were of Jewish ancestry.

Shortly after World War II started on 3 September 1939, on 20 November 1939 the Stettiner family closed their Paris gallery in Avenue Matignon.

In 1943, Stettiner was arrested, and afterwards imprisoned in La Grande Caserne Denis.

He survived the war along with his siblings Alphonse and Adele, with Stettiner dying in 1948.

[2] Stettiner's grandson hired Mondex, a Canadian company that is paid a 39 1/2 percent recovery fee that alleges Stettiner owned Seated Man with a Cane—that claim and the alleged attribution of ownership is now vigorously contested in a New York State lawsuit by the owner of the painting who legally acquired it at a London Christie's auction sale in 1996.