Cloning is the process of creating genetically identical offspring. Organisms that make clones of themselves do so through asexual reproduction. This involves just one organism. Sexual reproduction, on the other hand, creates genetically distinct offspring from two parents. Sexual reproduction creates diversity within a population by means of having distinct offspring. Cloning necessitates genetically identical offspring (save for a few mutations), and thus is incompatible with sexual reproduction.
In sexual reproduction, the male gamete contributes half of the genetic material. A spermatozoon contributes exactly 23 chromosomes, while an ovum contributes exactly 23 chromosomes.
