Epigenetics is the study of non-genotoxic, reversible, heritable changes in a gene's phenotype due to processes that occur without changing the underlying DNA sequence.
The two best understood epigenetic mechanisms include DNA methylation and histone modifications, but some recent advancements have been made to discover other processes such as noncoding RNA and prions that are impacted by epigenetics. Some of the disorders associated with anomalous epigenetics include cancer, Rett syndrome, Prader-Willi syndrome (PWS), Angelman syndrome, and BWS.

One of the most significant topics regarding epigenetics includes transgenerational inheritance as there are imprint control areas and transposable elements at which parental epigenetic marks are not erased.