Edith Heard is a geneticist and developmental biologist whose main area of research is understanding X-inactivation in cells, the process by which one X chromosome is switched off in the cells of female mammals. She has also shown that this process and mechanism differ strikingly in different species of mammals.

Edith developed new techniques for imaging DNA and genetic processes in cells. She discovered that the X chromosome is inactivated twice during embryonic development, once in cells developing into the placenta and again in cells that go on to form the embryo. This discovery has important implications for stem cell research as it implies that cells have plasticity.

Edith won the 2011 Grand Prize of La Fondation pour la Recherche Médicale, awarded for an exceptional contribution to medical knowledge. She is also a Professor of the Collège de France, where she regularly gives public lectures with the aim of explaining the importance and epigenetics and the science behind it.