In biology, and specifically genetics, epigenetics is the study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence – hence the name epi- (Greek: επί- over, above, outer) -genetics. It refers to functionally relevant modifications to the genome that do not involve a change in the nucleotide sequence. Examples of such changes are DNA methylation and histone modification, both of which serve to regulate gene expression without altering the underlying DNA sequence.

These changes may remain through cell divisions for the remainder of the cell's life and may also last for multiple generations. However, there is no change in the underlying DNA sequence of the organism; instead, non-genetic factors cause the organism's genes to behave (or "express themselves") differently.

One example of epigenetic changes in eukaryotic biology is the process of cellular differentiation. During morphogenesis, totipotent stem cells become the various pluripotent cell lines of the embryo, which in turn become fully differentiated cells. In other words, a single fertilized egg cell – the zygote – changes into the many cell types including neurons, muscle cells, epithelium, endothelium of blood vessels, etc. as it continues to divide. It does so by activating some genes while inhibiting others.

Bruce Harold Lipton (born October 21, 1944) is an American developmental biologist, who is best known for promoting the idea that genes and DNA can be manipulated by a person's beliefs. He teaches at the New Zealand College of Chiropractic.

Lipton was born in Mt. Kisco, an affluent town in New York. In 1966 he received a B.A. in Biology from C.W. Post Campus of Long Island University and then his PhD in developmental biology from the University of Virginia in 1971.

In 1973 he taught anatomy as an Assistant Professor at the University of Wisconsin School Of Medicine before coming to St. George's University School of Medicine, where he became a Professor of Anatomy for 3 years. From 1987 to 1992 he was involved in research at Penn State and Stanford University Medical Center. Since 1993 he has been teaching in non-tenure positions at different universities. His publications consist mainly of research on the development of muscle cells.

Lipton has appeared on several radio shows as well as The Elaine Smitha Show and The Joe Rogan Experience podcast episode 165.

David Shenk is an American writer, lecturer, and filmmaker. He is author of six books, including The Genius in All of Us (2010), Data Smog (1997), The Forgetting (2001), and The Immortal Game (2006), and has contributed to National Geographic, Slate, The New York Times, Gourmet, Harper's, Wired, The New Yorker, The New Republic, The Nation, The American Scholar, NPR and PBS. In mid-2009, he joined TheAtlantic.com as a correspondent. He is a 1988 graduate of Brown University.

Shenk has published the following books:

In 2004, PBS broadcast the Emmy award-winning "The Forgetting," which was inspired by Shenk's book of the same name. The film was directed by Elizabeth Arledge. Shenk appeared in the film and served as a writer and consultant.[2]

In 2006, "The Forgetting" was featured on-screen and read aloud in the Sarah Polley film "Away From Her." Polley said that the book was "hugely influential" to her in making the film.

In 2007, Shenk wrote, produced and directed four short films on Alzheimer's disease.[3]