The study of epigenetics, or the study of changes in gene expression that are not caused by changes in the sequence of DNA (Bird, 2007), has intrigued scores of scientists over the past few decades. It is these epigenetic mechanisms that can influence whether one’s genes are switched on or off (i.e., gene expression). It may be through epigenetic mechanisms that environmental factors like diet, stress, prenatal nutrition, or prenatal drug exposure can lead to changes in gene expression from one cell to its daughter cells and, in some cases, from one generation to the next. Work in this area has focused on examining four main modes of epigenetic gene regulation: DNA methylation, imprinting, histone modification, and noncoding RNA-mediated gene regulation, especially by microRNA (miRNA). For a more comprehensive review on these four modes of epigenetic regulation, as well as on the technological advances which have made it possible to measure such changes, please see (Maccani & Marsit, 2009).
