Classic genetics alone is unable to explain the diversity we see within a population of living things.  This also cannot explain how identical twins with the same DNA sequences can have differences in their traits and development of disease.  First introduced in 1939 by C.H. Waddington, epigenetics is now able to offer some explanation, as it studies the heritable changes in gene expression that are not due to any alteration in the DNA sequence.

This may help to answer many questions.  How can we have so many different types of cells and they all carry the same genetic information?  How is More >