Epigenetics refers to DNA and chromatin modifications that play an important role in the regulation of various genomic functions. This important book reviews human and cellular data that underline paradoxical findings with respect to the contribution of heredity and environment to phenotype. The contributors then reinterpret these experiments that incorporate epigenetic factors. Topics include DNA methylation, histone modifications, chromatin modifications, the role of epigenetic modifications and environment on gene expression, and integrating genomic medicine into clinical practice.