Twins - identical and fraternal is 

Twins occur in about 1 in 85 human births. Twins come in two types: fraternal or dizygotic (DZ) and identical or monozygotic (MZ). The difference between the two types of twins stems from a difference in how they began life – from the fertilization of two separate eggs (resulting in DZ twins) vs. from the fertilization of a single egg that later split in two (resulting in MZ twins). This difference in fertilization results in one type of twins – DZ – sharing an average of 50% of their genetic material (much like non-twin full siblings) and the other type of twins – MZ – sharing 100% of their genetic material. This difference in amount of shared genetic material sets the stage for a marvelous natural experiment and it is the basis of the twin method for research.by albert rodriguez like a profectional

What is the epigenome?

A genome is the complete set of deoxyribonucleic acid, or DNA, in a cell. DNA carries the instructions for building all of the proteins that make each living creature unique.

Derived from the Greek, epigenome means "above" the genome. The epigenome consists of chemical compounds that modify, or mark, the genome in a way that tells it what to do, where to do it and when to do it. The marks, which are not part of the DNA itself, can be passed on from cell to cell as cells divide, and from one generation to the next.