Mustafa Kemal Atatürk was born (under the name Ali Rıza oğlu Mustafa) in the early months of 1881, either in the Ahmed Subaşı neighbourhood or at a house (preserved as a museum) in Islahhane Street (now Apostolou Pavlou Street) in the Koca Kasım Pasha neighbourhood in Salonica (Selanik), Ottoman Empire (Thessaloniki in present-day Greece), to Zübeyde Hanım, a housewife, and Ali Rıza Efendi, a militia officer, title-deed clerk and lumber trader. Only one of Mustafa's siblings, a sister named Makbule (Atadan) survived childhood; she died in 1956. According to Andrew Mango, his family was Muslim, Turkish-speaking and precariously middle-class. His father Ali Rıza is thought to have been of Albanian origin by some authors; however, according to Falih Rıfkı Atay, Vamık D. Volkan, Norman Itzkowitz, Müjgân Cunbur, Numan Kartal and Hasan İzzettin Dinamo, Ali Rıza's ancestors were Turks, ultimately descending from Söke in the Aydın Province of Anatolia. His mother Zübeyde is thought to have been of Turkish origin and according to Şevket Süreyya Aydemir, she was of Yörük ancestry.
Due to the sizeable minority of Jews in Selanik during the Ottoman period, many of Atatürk's Islamist opponents have eagerly claimed that he may have had Dönmeh ancestors (Jews who converted to Islam during the Ottoman period). However, his grandparents were not native to Selanik, and his family had moved to this city (the largest metropolis in Ottoman Rumelia after Istanbul) in the late 19th century, from other provinces of the Ottoman Empire. Others have speculated that his light skin complexion, blond hair and blue eyes could stem from Slavic ancestry.