"If we think of the genome as sentences, your DNA - or letters - are what is inherited from your father and mother," he continued. "The DNA methylation is like the punctuation marks that determine how the letters should be combined into sentences and paragraphs that are read differently in the different organs of the body - the heart, the brain, and so on. What we've learned is that these punctuation marks are attentive to signals that come from the environment, and that they take cues from living conditions in childhood. Essentially, they act as a mechanism, we believe, for adapting the DNA to the fast-changing world."