Marc Lépine was born Gamil Rodrigue Liass Gharbi on October 26, 1964, in Montreal, Quebec, the son of Algerian immigrant Rachid Liass Gharbi and Canadian nurse Monique Lépine. Gamil's sister, Nadia, was born in 1967. Rachid was a mutual funds salesman and was travelling in the Caribbean at the time of his son's birth. During his absence, Monique discovered evidence that her husband had been having an affair. Rachid was a non-practising Muslim, and Monique a former Catholic nun who had rejected organized religion after she left the convent. Their son was baptized a Catholic as an infant, but received no religious instruction during his childhood; his mother described her son as "a confirmed atheist all his life".