Epigenetics is the study of a group of mechanisms that cells use to turn genes on or off, or to turn a gene’s activity (also called gene expression) up or down. There is also an element to these mechanisms that involves a memory of how a cell’s parent, grandparent or even further back has expressed these genes. One popular analogy for the interplay between genetics and epigenetics is to think of the human body as a computer. DNA is the hard drive and the epigenetics is the software which is driving the computer. The software tells the hard drive which tasks to perform and when but without the hard drive the software would have nothing to run on.