Abstract
In this chapter, we will discuss that the epigenome has a memory function in both somatic and germ cells. The latter is the basis for transgenerational inheritance. The master example of the transgenerational epigenetic inheritance concept is the agouti mouse model. However, also different types of human cohorts as well as “natural experiments” allow studying the impact of epigenetics on a population level. The progressive decline in the function of cells, tissues and organs associated with aging is affected by both genetic and epigenetic factors, i.e., there are characteristic epigenome-wide changes during aging acting as epigenetic clocks over years and decades. In contrast, epigenetic circadian clocks in the brain as well as in peripheral tissues coordinate a large set of physiological functions over a day.