Imagine you had a long lost twin which you were separated from at birth, you lived separate lives for 60 years and finally met up after all that time. Would they look the same as you? Be the same height and weight? The correct answer would most likely be no, you would probably not be the same height, have the same personality or have exactly the same face. Because the different lives you've lived have shaped you epigenetically and set you apart from your twin.
The body changes gene expression two ways, through histone proteins and methyl groups which bind onto DNA. Methyl groups and DNA go hand in hand, as the methyl groups tell the DNA what to do. All cells in the body have the same genetic code, but they all have different jobs and functions to perform and the methyl groups tell the cells what their job is. The difference between an eye cell and a red blood cell is the suppression of different sections of genetic code by methyl groups, which causes a specific expression. Histones on the other hand, act like spools which tighten or loosen the DNA strands exposing different sections so that they may be expressed. Together they can completely change gene expression and govern the cellular behavior of an individual.
A methyl group binding to DNA
Understanding how we operate epigenetically opens up so many scientific possibilities for getting exactly what we want from the genetic information we have inherited and allows possibly a non manipulative method of genetic change. This branch of research offers an incredibly in depth look at ourselves, changing our views on how the past has affects us, and shedding a new light on how what we do right now will affect those who come after us.
Learn Genetics (2012), IDENTICAL TWINS: PINPOINTING ENVIRONMENTAL IMPACT ON THE EPIGENOME