MZ twins also known as Monozygotic twins are identical twins, who develop from a single fertilized egg that divides into two (2) embryos. See also Dizygotic twins; identical twins, or twins that share 100% of their genetic material. Twins that derive from a single zygote that has split into two (2) identical twins. Each MZ twin carries the same genetic code. Please see also Monozygotic (identical) twins and Monozygotic (MZ) twins