Abstract
In this chapter, we will present that early embryonic development is very vulnerable to environmental influences. Therefore, from all phases of our life, embryogenesis is the period, where epigenetics has the largest impact. Epigenetics directs the programing of PGCs, induced pluripotency as well as the function of adult stem cells in tissue homeostasis. These master examples demonstrate the impact of epigenetics on the organization of our body in health and disease. Epigenetic regulation is also critical for the normal development and functioning of our brain. Dynamic DNA and histone methylation as well as their demethylation at specific gene loci play a fundamental role in learning, memory formation and behavioral plasticity. Thus, the epigenome of neurons allows a molecular explanation for long-term memories.