Irena Sendler was born as Irena Krzyżanowska on 15 February 1910 in Warsaw, but spent most of her youth in Otwock, a town with a vibrant Jewish community. Her parents were Dr.Stanisław Krzyżanowski, a physician, and his wife, Janina. They were members of the Polish Socialist Party. At the end of World War I, a typhus epidemic broke out, and Irena’s father, Dr. Krzyzanowski, devoted himself to caring for impoverished Jews suffering from the disease. He contracted typhus from his patients and passed away. Irena was just seven years old. She and her mother eventually returned to Warsaw.