Louis Slotin was the first of three children born to Israel and Sonia Slotin, Yiddish -speaking Jewish refugees who had fled the pogroms of Russia to Winnipeg, Manitoba. He grew up in the North End neighborhood of Winnipeg, an area with a large concentration of Eastern European immigrants. From his early days at Machray Elementary School through his teenage years at St. John's High School, Slotin was academically exceptional. His younger brother, Sam, later remarked that his brother "had an extreme intensity that enabled him to study long hours."