“Epigenetics” is now used with both classical and recently-revised definitions. Classical defintions of “epigenetic” emphasize influences of variations that are not encoded in primary DNA sequence but nevertheless inherited “… a change in the state of expression of a gene that does not involve a mutation, but that is nevertheless inherited in the absence of the signal (or event) that initiated the change” [98]. However, more recent definitions of “epigenetic” emphasize gene regulatory mechanisms that do not alter primary DNA sequence while paying less attention to documenting heritability [98].
