Born in Warsaw on 20 August 1930, Olszewski originated from a working-class family employed in the railway industry who were strongly connected to the Polish Socialist Party.
Lahir di Warsawa pada 20 Agustus 1930, Olszewski berasal dari keluarga kelas pekerja yang bekerja di industri kereta api, yang sangat terhubung dengan Partai Sosialis Polandia.