what are monozygotic twins

Monozygotic twins, also known as identical twins, are twins that result from the fertilization of a single egg by a single sperm, with the fertilized egg then splitting into two. This means that monozygotic twins share the same genetic information and are always of the same sex. Monozygotic twins are formed when a single fertilized egg divides into two after fertilization. Monozygotic twins are nearly 100% genetically identical, and both of them invariably have the same blood type and are of the same sex. Monozygotic twins are different from fraternal twins, also known as dizygotic twins, which result from the fertilization of two separate eggs with two different sperm during the same pregnancy. Fraternal twins share half of their genomes, just like any other siblings, and may not be of the same sex or have similar appearances.