The wedding portrait of John Paul II's parents, Emilia and Karol Wojtyła Snr
Karol Józef Wojtyła was born in the Polish town of Wadowice. He was the youngest of three children born to Karol Wojtyła (1879–1941), an ethnic Pole, and Emilia Kaczorowska (1884–1929), whose mother's maiden surname was Scholz. Emilia, who was a schoolteacher, died from a heart attack and kidney failure in 1929 when Wojtyła was eight years old. His elder sister Olga had died before his birth, but he was close to his brother Edmund, nicknamed Mundek, who was 13 years his senior. Edmund's work as a physician eventually led to his death from scarlet fever, a loss that affected Wojtyła deeply.
As a boy, Wojtyła was athletic, often playing as . During his childhood, Wojtyła had contact with Wadowice's large Jewish community. School football games were often organised between teams of Jews and Catholics, and Wojtyła often played on the Jewish side. "I remember that at least a third of my classmates at elementary school in Wadowice were Jews. At elementary school there were fewer. With some I was on very friendly terms. And what struck me about some of them was their Polish patriotism." It was around this time that the young Karol had his first serious relationship with a girl. He became close to a girl called Ginka Beer, described as "a Jewish beauty, with stupendous eyes and jet black hair, slender, a superb actress."
In mid-1938, Wojtyła and his father left Wadowice and moved to Kraków, where he enrolled at the Jagiellonian University. While studying such topics as philology and various languages, he worked as a volunteer librarian and was required to participate in compulsory military training in the Academic Legion, but he refused to fire a weapon. He performed with various theatrical groups and worked as a playwright. During this time, his talent for language blossomed, and he learned as many as 12 languages — Polish, Latin, Italian, Spanish, Portuguese, French, English, German, Ukrainian, Serbo-Croatian, Slovak and Esperanto, nine of which he used extensively as pope.
In 1939, Nazi German occupation forces closed the university after invading Poland. Able-bodied males were required to work, so from 1940 to 1944 Wojtyła variously worked as a messenger for a restaurant, a manual labourer in a limestone quarry and for the Solvay chemical factory, to avoid deportation to Germany. In 1940 he was struck by a tram, suffering a fractured skull. The same year he was hit by a lorry in a quarry, which left him with one shoulder higher than the other and a permanent stoop. His father, a former Austro-Hungarian non-commissioned officer and later officer in the Polish Army, died of a heart attack in 1941, leaving Wojtyła as the immediate family's only surviving member. "I was not at my mother's death, I was not at my brother's death, I was not at my father's death," he said, reflecting on these times of his life, nearly forty years later, "At twenty, I had already lost all the people I loved."
After his father's death, he started thinking seriously about the priesthood. In October 1942, while the war continued, he knocked on the door of the Bishop's Palace in Kraków and asked to study for the priesthood. Soon after, he began courses in the clandestine underground seminary run by the Archbishop of Kraków, Adam Stefan Cardinal Sapieha. On 29 February 1944, Wojtyła was hit by a German truck. German Wehrmacht officers tended to him and sent him to a hospital. He spent two weeks there recovering from a severe concussion and a shoulder injury. It seemed to him that this accident and his survival was a confirmation of his vocation. On 6 August 1944, a day known as "Black Sunday", the Gestapo rounded up young men in Kraków to curtail the uprising there, similar to the recent uprising in Warsaw. Wojtyła escaped by hiding in the basement of his uncle's house at 10 Tyniecka Street, while the German troops searched above. More than eight thousand men and boys were taken that day, while Wojtyła escaped to the Archbishop's Palace, where he remained until after the Germans had left.
On the night of 17 January 1945, the Germans fled the city, and the students reclaimed the ruined seminary. Wojtyła and another seminarian volunteered for the task of clearing away piles of frozen excrement from the toilets. Wojtyła also helped a 14-year-old Jewish refugee girl named Edith Zierer, who had escaped from a Nazi labour camp in Częstochowa. Edith had collapsed on a railway platform, so Wojtyła carried her to a train and stayed with her throughout the journey to Kraków. Edith credits Wojtyła with saving her life that day. B'nai B'rith and other authorities have said that Wojtyła helped protect many other Polish Jews from the Nazis. During the Nazi occupation of Poland, a Jewish family sent their son, Stanley Berger, to be hidden by a Gentile Polish family. Berger's biological Jewish parents died during the Holocaust, and after the war Berger's new Christian parents asked Karol Wojtyła, the future Pope John Paul II, to baptise the boy. Wojtyła refused, claiming that the child should be raised in the Jewish faith of his birth parents and nation, not as a Catholic. He did everything he could to ensure that Berger leave Poland to be raised by his Jewish relatives in the United States. In April 2005, shortly after John Paul II's death, the Israeli government created a commission to honour the legacy of John Paul II. One of the ways of honour, proposed by Emmanuelle Pacifici, the head of Italy's Jewish community, was the medal of the Righteous Among the Nations. In Wojtyła's last book, Memory and Identity, he described the 12 years of the Nazi régime as "bestiality", quoting from the Polish theologian and philosopher Konstanty Michalski.