are monozygotic twins genetically identical
Monozygotic twins have very similar, but not identical DNA. Monozygotic twins come from a zygote that divides into two. Boy/girl twins are always fraternal -- or dizygotic, as they can only form from separate eggs fertilized by separate sperm.nother difference between monozygotic twins and dizygotic twins is that only monozygotic twins can be conjoined, which means that some parts of their bodies are joined or shared. Many scientists believe that this occurs when the original zygote begins to separate after more than 12 days and is unable to fully divide.