In Chance and necessity and The Logic of life (both published in 1970), Jacques Monod and François Jacob attributed a central role to cybernetics. This approach was nevertheless ambiguous, as their vision of molecular biology did not include interdisciplinary collaboration with systems scientists. This paradoxical attitude, neglected by historians, calls for a better assessment of the conceptual and practical continuities and discontinuities between cybernetics and molecular biology. This paper contributes to such an assessment by revisiting the cybernetic themes in these books. It follows the logical and chronological order of the circulation of these ideas by contextualizing these themes within two successive frameworks : the first part of the paper deals with the biological thinking of Norbert Wiener, and shows that it is not entirely cybernetic (especially regarding heredity). Part 2 questions the status of the cybernetic vocabulary used by Monod and Jacob in light of their rejection of interdisciplinary collaboration with systems scientists for developing models of complex networks. The final part examines the place of cybernetics in the two books through the concepts of information, program, and teleonomy. From Wiener to Monod and Jacob, the thinking of heredity as the replication of a genetic program featuring mutational noise remained in the line of neo-Darwinism and the « central dogma » of molecular biology : the program would control feedback mechanisms in the body, without including its own feedback mechanism to adapt and learn from experience. Thus, in retrospect, Monod and Jacob’s biology was moderately cybernetic, and its continuity with Wiener’s biological thinking was not based solely on the cybernetic idea of opposing entropy through feedback mechanisms.