 His great-grandfather, Jacques Dupré, was a pioneer of St. Landry Parish who served as a National Republican governor of Louisiana from 1830 to 1831 and in the Louisiana State Senate during the 1830s and 1840s.Gilbert was only ten when his father, Lucius, who was a law graduate of the University of Virginia and a member of the former Confederate Congress, died.There was no money for Gilbert's education; so he was self-educated in the law while he worked first in the office of the St. Landry Parish clerk of court.