Definition of Epigenetics
Epigenetics is the branch of genetics that is the study of mechanisms through which the gene expressions are changed while passing from one cell to the other. These modifications are external and they only turn the genes on and off and they do not affect the sequence of DNA. Moreover, these changes can be reversed too.
Examples of Epigenetics:
The physical structure of the genetic material is modified either by the addition of methyl group to the DNA molecule which does not let certain genes express themselves or by squeezing the histone structure that would not let the cell read the structure of DNA. It is due to epigenetics that the cells of skin and brain look different from each other.