 As his mother worked six days a week, he was mainly brought up by his mother's stepfather, Ludwig Frahm (1875–1935), and his second wife, Dora.He joined the "Socialist Youth" in 1929 and the Social Democratic Party (SPD) in 1930.He left the SPD to join the more left wing Socialist Workers Party (SAP), which was allied to the POUM in Spain and the Independent Labour Party in Britain.