Élisabeth was born in Paris to a wealthy bourgeois French family of Corsican descent. She had had hepatitis as a child, and it recurred throughout her life with attacks of varying severity. She met medical doctor Félix Leseur (1861–1950), also from an affluent, Catholic family in 1887. Shortly before they married on 31 July 1889, Élisabeth discovered that Félix was no longer a practicing Catholic. Dr. Félix Leseur soon became well known as the editor of an anti-clerical, atheistic newspaper in Paris. Well-to-do by birth and marriage, she was a part of a social group that was cultured, educated, and generally antireligious. The attachment of the couple was strong, though overshadowed by the childlessness of the marriage and their ever-growing religious disagreement.