Twins are two offspring from the same pregnancy, usually born close together. They can be the same or different sex. Identical twins result from one fertilized egg that splits, while fraternal twins develop from two separate eggs fertilized in the same pregnancy. Cloning is the process of producing genetically identical individuals, and it occurs naturally in some species or can be done through DNA transfer techniques in biotechnology and molecular biology. Asexual reproduction involves a single parent where the offspring is genetically identical, and it can occur through various cell division or budding processes.