Sibylle Gabrielle de Mirabeau was born at the Château de Koëtsal (or Coétsal) in Brittany. She was a direct descendant of the famous reactionary aristocrat of the French Revolution, André-Boniface-Louis de Riquetti, vicomte de Mirabeau, known as "Mirabeau-Tonneau." Her mother, the comtesse de Mirabeau, née de Gonneville, was also a writer. In 1869, she married comte Roger de Martel de Joinville, with whom she had three children. Known for her fanatical anti-Semitism, she also hated democracy and republicanism. Using the pseudonym Gyp, she produced more than 100 popular novels containing detailed descriptions of fashonable French society of the period. Among the best known of her works are Petit Bob (1868), which introduced the type of "enfant terrible," Le Mariage de Chiffon (1894), Autour de Divorce (1886), and On Menages Dernier Cri (1903). Gyp also published several volumes of memoirs including Souvenirs d’une petite fille (1927–1928) and La Joyeuse Enfance de la III Republique (1931).