ABSTRACT
This chapter discusses the vibrant sub-field known as behavioral epigenetics. Conrad Hal Waddington recognized that the metaphor of the epigenetic landscape had limitations, nevertheless it is usually assumed to be the starting point for a genealogy of epigenetics. Robust findings make clear that, independently of developmental processes, environments both external and internal to the body bring about epigenetic alterations in the genome that are deeply involved with health and illness throughout life. In other words, the environment can "sculpt the genome and affect the phenotype throughout life". Chromatin, the "stuff" of chromosomes, the task of which is to compact DNA, is composed of DNA, RNA, proteins, among which are histones, and yet other molecules. Small amounts of DNA are wound around eight histones to form a beadlike structure–the nucleosome–from which parts of the histone molecules protrude. DNA is not changed directly by environmental exposures.
