Jon_C_What_is_epigenetics

Because a couple people have asked this question, I've decided to put together a primer on epigenetics.

The word "epigenetics" comes from C.H. Waddington, who coined the term as a neologism of "genetics" and "epigenesis," around 1939. Originally, he intended for it to be limited to epigenesis, or the development of an organism through successive differentiation of cells (as opposed to a [|homoncular] mode of development). The meaning has shifted slightly in recent history, as the field of epigenetics has developed, into a term that includes every type of biological inheritance that resides outside of the genome. Most of the research that is being done today is on DNA [|methylation], which creates a change in the readability of the particular gene, essentially turning genes on and off by interfering with RNA polymerase, but not DNA polymerase. The specificity of this action is important, as it does not interfere with the replication of DNA (epigenetic information is "stripped" before replication), but only the production of RNA (and consequently proteins). This kind of methylation has been shown to be transferrable from parents to children, and allows for gametes (and somatic [bodily] cells) to be changed by the environment (e.g. smoking, environmental toxins such as BPA all change the methylation patterns).