Someone asked: Do you consider the following a solid definition of epigenetics?
Epigenetics” refers to chemical modifications of the human genome that alter gene activity without changing the DNA sequence. DNA is wrapped around proteins called histones, and both DNA and the histones are covered with chemical “tags.” These histones and chemical tags (or “epi-marks”) are part of each person’s epigenetics, constituting an extra layer of information attached to our genes’ backbones that regulates their expression.
Jonathan Wells writes to tell us, “The definition you cite corresponds to the narrower definition but it ignores the larger definition. The narrower definition describes some real phenomena, but it is embraced by people who do not want to upset the neo-Darwinian applecart.” In other words, the narrower definition softpedals the damage epigenetics does to modern Darwinism. Wells kindly permitted us to reproduce a section on epigenetics from his 2017 book Zombie Science: More Icons of Evolution:
In 1942, British biologist Conrad Waddington introduced the word “epigenetics” to mean the study of “the processes involved in the mechanism by which the genes of the genotype bring about phenotypic effects.”  Three years earlier, however, Waddington had coined the word “epigenotype” to refer more broadly to “the set of organizers and organizing relations to which a certain piece of tissue will be subject during its development.”  From the beginning, then, epigenetics had more than one meaning. In a narrow sense, it referred to the mechanisms by which genes produce phenotypic effects. In a broad sense, it referred to all of the factors involved in development, only one of which is the genome.
Most biologists now use epigenetics in its narrow sense to refer to heritable changes in the structure of a chromosome that do not change the underlying DNA sequence. In 2007, biologist Julie Kiefer wrote, “Epigenetics is the study of heritable changes in gene function that occur independently of alterations to primary DNA sequence.”  These “epigenetic” changes in turn affect when and where specific parts of a DNA sequence are transcribed into RNA. Epigenetics in this narrow sense leaves [neo-Darwinism] essentially intact.
But some biologists understand epigenetics more broadly. In 1993, Susan Herring wrote, “Broadly speaking, ‘epigenetics’ refers to the entire series of interactions among cells and cell products” leading to embryo development.  In 2002, Eva Jablonka and Marion Lamb wrote that epigenetics is “primarily concerned with the mechanisms through which cells become committed to a particular form or function… Recognizing that there are epigenetic inheritance systems through which non-DNA variations can be transmitted in cell and organismal lineages broadens the concept of heredity and challenges the widely accepted gene-centered neo-Darwinian version of Darwinism.”  33. Conrad H. Waddington, “The epigenotype,” Endeavour 1 (1942): 18–20. 34. Conrad H. Waddington, An Introduction to Modern Genetics (London: George Allen & Unwin, 1939), 156. 35. Julie C. Kiefer, “Epigenetics in development,” Developmental Dynamics 236 (2007): 1144– 1156. doi:10.1002/dvdy.21094. PMID:17304537. 36. Susan W. Herring, “Formation of the vertebrate face: Epigenetic and functional influences,” 37. American Zoologist 33 (1993): 472–483. doi:10.1093/icb/33.4.472. Eva Jablonka and Marion J. Lamb, “The changing concept of epigenetics,” Annals of the New York Academy of Sciences 981 (2002): 82–96. doi:10.1111/j.1749-6632.2002. tb04913.x. PMID:12547675. pp. 89-90 of (copyright 2017 Discovery Institute)
To the extent that the Darwin-in-the-schools lobby permits the discussion of epigenetics, we can be reasonably sure they restrict it to the narrower, less threatening sense. And what better stronghold for Darwinism than the public school, which all taxpayers are forced to fund and most parents obliged to send their kids to?
See also: Epigenetic change: Lamarck, wake up, you’re wanted in the conference room!