Epigenetics studies changes in gene expression due to aging or other factors, involving DNA methylation, histone modifications, and chromosome packing.

“Epigenetics basically is the study of the changes that happen in cells whether as a result of aging or as a result of anything else, that cause differences in which genes are turned on and which genes are turned off. So typically, these will range from things at the DNA level itself, methylation of cytosines for example, up through modifications of histones, these proteins that DNA is wrapped around, up through higher level changes to the packing of chromosomes and to chromatin an awful lot of different things change the behavior with which a cell actually decides which proteins to express and which ones not to.”