Epigenetic modification: An epigenetic modification is a chemical change in DNA or in proteins around which DNA is wrapped to form chromatin (main component of chromosomes) that promotes or inhibits its reading, and thus gene expression. Such a change can be caused by our behaviour or our environment, and can be passed on to our offspring. In contrast to mutations, epigenetic modifications do not affect the DNA sequence, but propose a different “reading” of it. In the analogy of DNA as a vast recipe book, a mutation is a change in the text, for example a 600 becoming an 800; in contrast, an epigenetic modification is, without a change in the text, a defect that renders one or more recipes unworkable, like two pages stuck together. Like a mutation, such a modification can lead to a better adaptation to the environment, but also to dysfunctions (e.g. cancers).