Mother Jones' Joe Kloc this week presents his "illustrated guide to epigenetics" — four figures are paired with explanatory text that describes the processes of methylation and histone modification for a lay audience. Kloc explains epigenetics by answering his own straightforward questions, such as "How can different types of epigenomes develop from the same genome?" and "Why do scientists care?" He says that if the genome is a "how-to manual that contains instructions for every possible task required for a complex living creature to survive," then the epigenome "tells each cell which part of the manual to read."