Twins seem, on the outside, to be very similar and identical.
But when you meet each one and get to know them, you realize they are very
different from each other. The question is: Why? Is it the environment? But
they have lived in the same house, mostly likely experienced similar things,
and ate parallel foods for the first 18 years of their lives. For example, in
one pair of twins, one sister is very confident, has been married, and has a
very different fashion sense than that her twin who has serious depression
issues, is more conscientious, been divorced, and suffered from leukemia. They’re
still twins, but very different lives.
Scientists have discovered that this
difference in lives is due to epigenetics in the human epigenome. Epigenetics
is the mechanism where environmental changes alter the behavior of our genes.
Specifically, methyl, a chemical within our cells, can attach itself to our DNA
and can turn down or up the activity of a gene and stop it from making certain
proteins. Levels can fluctuate with all different kinds of life events like
aging, diet, illness, chemicals, smoking, drugs, medications and more. So the
reason these twins are so different is because some of their genes have been switched
on in one case and off in another. Some are positive affects, and some are
negative, like depression and susceptibility to diseases.