If your partner was an identical twin...?

It would seem a bit strange yes. But recent genetic research has in fact shown that identical twins are not 100% genetically identical, contrary to popular belief. Identical twins differ from one another in the number of copies of some of their genes. This is known as Copy Number Variance. This is only the case for a small percentage of genes. However, it is a significant cause of difference between identical twins. Another cause of difference is epigenetics. Certain molecules close to a person's genes can and do alter the struture of their genes over their lifetime, causing the output of the gene to be different to what it was before the change. This process is irreversable. Identical twins genes are affected differently by this process, meaning that the twins become more and more different as they age. These changes are irreversable and are ped on to the next generation. Every person on this earth is genetically unique, regardless of whether they are an identical twin or not.