We have spoken a lot about how our DNA has instructions  to build and maintain all life on Earth. It slowly changes over time through evolution. It also changes quicker via sex. Sex brings two different DNA and epigenetics together to form a new and unique life form. The Universe we live in is constantly changing. Earth has changed many times over its existence. As changes occur, we need to be able to adapt quickly or perish. Our epigenome is the pattern of epigenetic switches that are turned ON and OFF. Theses which enable or disable certain DNA genes. The combination is vast and very complex. It allows living creatures and plants to react to environmental changes that face them. These changes can be diet, stress, heat/cold, sun, toxins, etc. Basically we are trying to adopt to drastic changes so the species can continue. Sometimes our epigenetic changes cause illness or death and that part of the species stops existing. Other parts find combinations that work, they adopt and continue to produce new members of the species. Sometimes whole species die out like the dinosaurs and other times a species evolves into a different type of specie. Life goes on if it can find epigenetic and genetic changes that allow it to survive with a food source, stress levels and environmental changes. The University of Utah has an epigenetic primer that is worth studying,