Fraternal twins are likely to be formed by 2 different egg cells being simultaneously sent by the ovaries and both of them being fertilized by the sperm cells. They are non-identical because the DNA of the 2 egg cells and the 2 sperm cells are different.
Identical twins are formed after a single egg cell has been fertilized by a single sperm cell, then split after the first division. This results in 2 genetically identical embryos because they were formed from the same fertilized egg.
Answer: fraternal twins happen when superset sperms enter separate eggs but they fertilize together. Identical happen when the fertilized egg divided in two while it is still a tiny collection of cells. The sled contained halves then develop into two babies with the same genetic information.
