The Human Genome Project .gov site shows the first description of the Human Methylome. What is a methylome? It is the epigenetic control of genes by methylation.

Epigenetics is the control of gene expression through non-DNA methods. It actually controls access to the 3 billion base pair sequence. It's like controlling the spools on which a large wire is wound. Methylation is usually (but not always) on the CG base pairs. Methylation involves cell differentiation during the development of the embryo. So, again, controlling genetic expression through the epigenetic process METHYLATION could result in the development of stem cells from differentiated cells.

So, ways of longevity, like Valter Longo's Mimicked Fasting, Nir Barzilai's TAME study, and David Sinclair's NMN are all ways of jump-starting or rekindling the expression of genes that were active when we had younger, more active metabolism. Examples including mTOR, AMPK, SIRT-1.

So, again, theoretically, if we can control methylation, we can control aging. (I don't, however, think that will happen any time soon.)