A pioneer of modern genetics, Dr. Lejeune discovered the chromosomal defect that causes Down''s. International acclaim followed, but more important to this doctor—dazzled by the beauty of every human life—was improving the care of his patients with this abnormality. As a man of both science and conscience, he advocated for their dignity, and he suffered attacks on his reputation as a result. To write this definitive biography, Aude Dugast spent eleven years consulting thousands of archives. She met at length with Lejeune''s wife and relatives, families of his patients, and his French and foreign collaborators. She invites us to discover the true and untold portrait of Jérôme Lejeune—brilliant scientist close to the great figures of this world, devoted husband and father, and ardent defender of the little ones.