Is it true that identical twins are 100% genetically identical throughout their lives?

Answer

Identical twins are indeed completely genetically identical, as they originated from one and the same cell. During your life, changes can occur in your DNA, for example as a result of UV rays, chemical substances, or others. This happens very locally, in other words not in all your cells. Apart from these minor differences, identical twins therefore remain 100% genetically identical for the rest of their lives.

This does not mean that you are completely identical, of course, because your DNA only partly says who you are. Your environment, upbringing and lifestyle also play a very important role in this.