ep·i·ge·nome 
(ĕp′ĭ-jēnōm)
(ĕp′ĭ-jēnōm)n.
The set of heritable chemical changes to an organism's genome, such as DNA methylation or histone modification, that modify gene expression but do not change the DNA sequence itself.
ep′i·ge·nomic (-jə-nōmĭk) adj.