Her father was a US citizen employed under contract with the United States Military Administration of Occupied Japan at the General Headquarters.
Vivienne Wilson had been weakened by the privations of World War II, and contracted tuberculosis during James Vaughn's absence to the United States, during which Mary Ann was cared for by a nanny, Fumi.
Vivienne died on 5 August 1950, the very day of passage of private legislation permitting her to immigrate to the United States.
She was buried in the Geijin Boche, the Foreign Cemetery overlooking the port in Yokohama, Japan.
Due to the privations of the postwar period, John Wilson sailed to Sweden with his wife and children in 1952.