Mirosław Hermaszewski was born into a Polish family in Lipniki, formerly in the Wołyń Voivodeship of Poland, but at the time part of Reichskommissariat Ukraine, and since the end of the Second World War located in Ukraine. The youngest of Roman Hermaszewski and Kamila Bielawska's seven children, Mirosław is a survivor of the Volhynian slaughter during which Ukrainian nationalists murdered 19 members of his family, including his father. Hermaszewski narrowly escaped death himself when the Ukrainian Insurgent Army attacked Lipniki on the night of 26–27 March 1943. At the time of the massacre, Hermaszewski was only 18 months old; the youngest victim from his family was 1.5 years old, while the oldest—Hermaszewski's grandfather—was 90.