Epigenetics: the study of heritable changes in gene expression (active versus inactive genes) that do not involve changes to the DNA sequence — a change in phenotype without a change in genotype — which in turn affects how cells read genes. An epigenetic change is a regular, natural occurrence that can also be influenced by several factors which include age, environment, lifestyle, and disease state. Chronic pain, such as low back pain, sciatica, and fibromyalgia may ultimately affect this as well. Epigenetic modifications can manifest commonly as the manner in which cells terminally differentiate to end up as skin cells, liver cells, brain cells, etc. And epigenetic change can have more damaging effects that can result in diseases. New and ongoing research is continuously uncovering its role in a variety of human disorders and fatal diseases. Epigenetic marks are more stable during adulthood, they are still thought to be dynamic and modifiable by lifestyle choices and environmental influence. It is becoming apparent that epigenetic effects do not just take place in the womb, but over the full course of human life. Another discovery is that epigenetic changes can be reversed. There are numerous examples that show how different lifestyle choices and environmental exposures can alter marks on DNA and play a role in determining health outcomes.