Ceran St. Vrain was the son of a French aristocrat who came to the United States in the late 18th century to escape the French Revolution. His father was Jacques Marcellin Ceran de Hault de Lassus Saint-Vrain (1770-1818), the third son of Pierre de Luzière. Jacques was previously an officer in the French navy and commander of the King's galiot "La Flèche " – the Arrow – and captain of militia. His mother was Marie Félicité Chauvet Dubreuil of St. Louis, Missouri, which had a predominately French population. His parents were married on April 30, 1796; they had a large family. One of Ceran's brothers was Felix St. Vrain. He became a US Indian agent and was killed in 1832 by the Sauk tribe, in what came to be known as the St. Vrain Massacre, during the Black Hawk War.