Sidqi was born into a middle-class Palestinian family in Jerusalem in 1905. His father Bakri Sidqi was a teacher of Turkish ancestry. His mother, Nazira Murad, came from a prominent Jerusalem mercantile family.[7] After an early education there, he joined his father in 1914 as the latter worked in other parts of the Ottoman Empire, and in his formative years he grew up in Damascus, Cairo and Jeddah in the Hejaz, where Bakri had joined Prince Faisal's campaign.[7] On returning to Palestine he became an employee of the Mandatory Palestine's Department of Posts and Telegraphs.[3] There he met Jewish workers who introduced him to Communism.[8] He spent three years, from 1925 to 1928, at the Comintern's Communist University of the Toilers of the East (KUTV, pronounced Kutvo),[9] and during his time there married a Ukrainian communist.[10] He developed contacts with Joseph Stalin, Nikolai Bukharin, Georges Marchais and Khalid Bakdash, the Kurdish leader of the Syrian Communist Party,[10] met Mao Zedong and got acquainted with the Turkish poet Nâzım Hikmet and members of the family of Jawaharlal Nehru.[7] He returned with his wife to Palestine in 1928, and they began to organise activities against the British Mandate authorities.[11][12]