The word "epigenetics" is so ambiguous and confusing that we shouldn't use it. It sounds impressive: like genetics, but more epi! What does it mean? Something about how cell types tend to remain the same cell type? Something about non-genetic inheritance or memory? Something else? The straightforward reason why cell types tend to remain the same type is: because of the regulatory molecules in them, like transcription factors and miRNA. Is that epigenetics?
Epigenetics: Core misconcept by Mark Ptashne
What Do You Mean, “Epigenetic”? by Carrie Deans & Keith A Maggert
They claim the word "epigenetic" originally came from the older word "epigenesis": interesting!
A critical appraisal of clinical epigenetics by Bernhard Horsthemke
The telling point is that these papers disagree with each other.
Avoiding the "epi" words would hugely promote clear communication and clear thinking in biological sciences!
Update 2026-10: Here are some nice explanations of cell type regulation, with lots of evidence.
Terminal selectors of neuronal identity by Oliver Hobert
"A key defining feature of terminal selectors is that they are not only required to initiate terminal differentiation programs but are continuously expressed throughout the life of the neuron (and animal) to maintain the differentiated state... The continuous expression of terminal selectors is often ensured through autoregulatory feedback mechanisms".
Maintaining differentiated cellular identity by Johan Holmberg & Thomas Perlmann
"regulatory cascades that act in development seem to generate end-point states consisting of transcription factor networks that by themselves are fully capable of providing a complete and sufficient instructive 'code' for the maintenance of cell-type-specific gene expression programs".