There is no single answer. A big chunk of Turks are descendants of Greek speaking Muslims who settled after 1920 during the Balkan population exchange. But they themselves were often descended from Ottoman soldiers who conquered the Balkans for the Sultans. Some claim that the real Turks in Turkey are the nomadic Turkoman but they are also very diverse. In Turkey they say that Turks from Central Asia are the pure stock but it’s denied by the Central Asians themselves. Kazakhs say that before the Mongol invasion they were White Blond people with blue eyes. Who knows? Ethnic identity, language and genetics are only occasionally overlapping. This happens everywhere.