It ???is the study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence.??? See <a href="http://en.wikipedia.org/wiki/Epigenetics">http://en.wikipedia.org/wiki/Epigenetics</a> (???The modern usage of the word in scientific discourse is more narrow, referring to heritable traits (over rounds of cell division and sometimes transgenerationally) that do not involve changes to