“Genes are merely the blueprint, epigenetics is the contractor." (Bruce Lipton 1944 - )

Epigenetics is a word we are hearing a lot about these days. Epigenetics refers to changes of gene expression that are not due to changes in the DNA sequence of the gene. 

Way back when I was  first taught  about genetics in school, the focus was on Mendelian genetics, and autosomal dominant and recessive genes.