Plant cloning is used to create hybrid strains of grains, fruit and vegetables, disease-resistant and high-yielding varieties reproduced exactly over and over. Advantages outweigh the cons from a commercial faming viewpoint; however, this lack of diversity does not occur in nature. As varieties offer different disease-resistance levels, diversity protects crops from susceptibility to one disease which could wipe out a species worldwide.
Cloning Dolly, the first cloned sheep from an undifferentiated cell by nuclear transfer, was a massive achievement for science; however, it is far too costly to be commercially viable for farmers and breeders. A pro of animal cloning is the exciting prospect of re-introducing a recently extinct species such as the Tasmanian Tiger, and its potential use for protecting other species nearing extinction. One disadvantage of animal cloning of an endangered species would also be its susceptibility of being wiped out by the same disease due to the identical genetic structure.
Stem-cell cloning has many pros due to its usefulness in regenerative medicine and cancer treatments and its hope for future potential, including organ cloning. Stem cells are harvested from the umbilical cord of newborns; parents can store their baby's stem cells or donate them for research. As stem-cell cloning does not generally involve fertilized human embryos it is more widely accepted by the public, but it still raises social and ethical issues because stem cells can be extracted from human fetuses and fertilized embryos.
The cloning of human parts certainly offers great hope for people on the organ donation list as it world greatly prolong many lives and also remove the organ-rejection tendency due to mismatched DNA. Cloning whole humans, for instance super-kids, raises more concerns as it creates an unfair advantage to normal kids and could be seen as messing with the natural law of equality. Diversity is the key to evolution, an issue which human cloning contradicts, a major con of human is the strong ethical, religious and social issues going down this path would create.