There is no such thing as identical where twins are concerned
Identical twins have identical genomes, but that is where it stops. There are subtle differences in their personalities, how they look, how they act and in their susceptibility to disease. How can this be?
It all depends on how the “epigenome” is modified by the environment, say scientists from Sydney’s Garvan Institute of Medical Research and Queensland Medical Research Institute, who have just completed an 8-year study involving 512 adolescent twins (128 identical twin pairs, as well as 128 non-identical twin pairs), with an average age of 14.15 years.
Read the full media release here.

