The expression of the genes in each organism undoubtedly responds to the stimuli of the environment in which the given organism lives. It is a mechanism that helps the organism adapt to environmental conditions, and this adaptation can to a certain extent be transferred to the next generation as hereditary information. As discussed in chapter 3 - Mutations: how they arise and what to do with them, modifications to DNA that cause a change in genetic information were mentioned. In some cases, this can be manifested by the creation of a protein that has different properties or function. If a change in the DNA is also transferred to the daughter DNA molecule, it becomes a mutation. However, the change caused by an epigenetic modification has a different character, especially since it is not a change to the DNA sequence. It does not change the information in the DNA itself, but it changes the way in which this information is realized. To put it simply, epigenetic modifications can turn genes on and off. The set of epigenetic information affecting gene expression is called the epigenome.