If your ancestors lived in the Ottoman Empire, there is a genealogy database online through the Turkish government's E-Devlet website. However, I think you need a Turkish ID number and you probably need to read Turkish in order to use it. It has info on not only Turks, but also Greeks, Armenians, Jews, Kurds, etc. who were living in the Ottoman Empire. The section on the website is Nüfus ve Vatandaşlık İşleri Genel Müdürlüğü (General Directorate of Population and Citizenship Affairs).