I think that it was last year that Scienctific American (SA), in two successive issues as I recall, had articles on the topic of epigenetics.
The topic, based upon discoveries which began in the early 1960s, has laid to rest the incredibly short-sighted term "junk DNA" which I had seen applied to 98% (IIRC) of the human genome which does not encode proteins. During the 1980s, I had the opportunity, following her lecture, to ask a noted molecular geneticist about the illegitimacy IMHO of the term "junk DNA". Her response was that although we did not know what it was, it was NOT junk.
It is quite interesting the introns were included in that stupid junk categorization and are now revealing their functions.
A major part of the epigenetic field is the utilization of methyl and acetyl groups in genomic processing to, evidently, supress certain genes where needed. That stuff is now known to be involved in genetic inheritance.
In additon to the sRNA (for short RNA) mentioned in the article, there is also the nomenclature of microRNA (mRNA) for which I receive updates from Google Search.
I bought the only book mentioned in the SA articles on the topic; "The Epigenome; Molecular Hide and Seek", edited by Stephan Beck & Alexander Olek, published by Wiley-VCH, 2003. It is a very informative book and was, frankly, a bit beyond me in places.