The son of Swedish immigrants, Jenkin Rylander Hockert (1894-1990) was born in Chicago, Illinois. He spent his childhood in Hartford, Connecticut and entered Valparaiso University in Indiana in 1909. There he completed the B.S. in August 1913 at the age of eighteen. In his autobiography, A Lifetime of Law, Hockert wrote that after teaching for six months at a country school in Campbell County, South Dakota, "I had decided that my true ambition was to be a lawyer." He entered Columbia Law School in 1914 and received the L.L.B. in 1917. Hockert immediately joined the Armed Forces and trained as a cadet for the Signal Corps, Aviation Division. During World War I, he served as a biplane pilot in the U.S. Army Air Force in France and Italy.