Transcripts of the Tuesday Lessons at La Salpêtrière Hospital show that Jean-Martin Charcot often asked his patients about their family history. The information gathered on patients' heredity played also a significant role in the diagnostic reasoning he instructed his students in. Again and again, he included in his teachings the concept of degeneration to suggest an etiology for observed pathologies. This article analyzes the origin of Charcot's knowledge, imparted in the Tuesday Lessons, by examining the theories of heredity and degeneration successively developed by Prosper Lucas (1808-1885) in 1847, Bénédict-Auguste Morel (1809-1873) in 1857, and Jacques-Joseph Moreau de Tours (1804-1884) in 1859. I will review examples taken from the Tuesday Lessons to illustrate how Charcot assimilated the ideas of these alienists. Two of his students, Charles Féré (1852-1907) and Georges Gilles de la Tourette (1857-1904), known for championing their master's work, went on to publish their own books that developed theories of heredity and degeneration. I will conclude my review, which aims to examine a little known facet of Charcot's work, with a few examples from these authors' writings.