Vilmos Apor de Altorja was born in 1892 as the sixth of eight children to the nobles Baron Gábor Apor (1851–98) and Countess Fidelia Pálffy ab Erdöd (1863–1934); one was stillborn and three died in their childhoods. One sister was Gizella and another was Henrietta who was his junior and an elder brother was Gábor. His elder brother served in World War I but later became a Hungarian delegate to the Holy See until his resignation in 1944 in protest of the German occupation of his homeland. His father died in his childhood due to complications from diabetes. His mother was strict but caring and imparted sage religious instruction to her children. He served as an altar server during his childhood and his love for the priesthood intensified to the stage where he harbored an interest in becoming a priest himself. Bishop Miklós Széchnyi was his uncle.