Epigenetics

Epigenetics typically means "above" or "on top of" genetics. It refers to external modifications to DNA that turn genes "on" or "off." These modifications do not change the DNA sequence, but instead, they affect how cells "read" genes. Epigenetic changes alter the physical structure of DNA. It can also define as "the study of the mechanisms of temporal and spatial control of gene activity during the development of complex organisms." Thus epigenetic can be used to describe anything other than DNA sequence that influences the development of an organism.