Rhonda J. Pomerantz, MD is a practicing Dermatologist (Skin Specialist) in New York, NY. Dr. Pomerantz graduated from New York University School of Medicine in 1989 and has been in practice for 28 years. She completed a residency at Suny Health Science Center. Dr. Pomerantz also specializes in Internal Medicine.
Identical twins form when one egg has been fertilised by one sperm and the zygote splits into two. This happens at the very earliest stage of development, when the zygote is no more than a cluster of a few cells.
The difference between fraternal and identical twins is that fraternal twins are two separate eggs fertilized by two separate sperm to form two separate embryos and then make two separate babies.Identical twins are formed when one fertilized egg divides into two separate embryos to make two babies.raternal, or dizygotic, twins happen when Mom releases two eggs (either at the same or different times during her cycle), and different sperm fertilize each egg. Fraternal twins share up to 50% of their genes, and are no more alike or different than any two siblings would be.