Monozygotic twins, also known as identical twins, are formed from a single fertilized egg that splits into two embryos. This process occurs in the early stages of development, resulting in two genetically identical individuals who share the same DNA. Because they originate from the same zygote, monozygotic twins often have similar physical characteristics and may even share the same gender. However, while they have identical genetic material, environmental factors can lead to differences in personality, interests, and health outcomes as they grow and develop.