monozygotic twins, identical twins

monozygotic twins, identical twins

or

uniovular twins

siblings that develop from one egg, contain identical genetical information, and are (usually) of very similar appearance. Any physical and mental differences detected between identical twins must arise, therefore, from environmental differences, both before and after birth. Such twins are examples of a CLONE and are always of the same sex. Compare DIZYGOTIC TWINS.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005