Negative aspects of cloning include developmental complications, abnormal genes and low success rates. The possibility also exists that a human clone could be unable to fully integrate into familial and society roles.
Cloning is largely unsuccessful because the process of somatic cell nuclear transfer is problematic. The overall success rate for a nucleus transfer is anywhere from 0.01 to 3 percent. There is also a high failure rate for pregnancies that stem from cloning. Another risk factor is the egg and nucleus not forming cohesively to complete the cloning process.
Animals that are cloned tend to be larger than their noncloned counterparts. This is known as Large Offspring Syndrome, and animals that suffer from it are prone to large organs, which causes breathing and bloodflow complications. Cloned animals also suffer from immune, brain and kidney problems.
There is also the probability that clones age faster due to an already worn transferred nucleus. Scientists are concerned that the chromosomes may have compromised properties that lead to enhanced aging. Experts warn about the developmental complications that can arise from this problem as well.
Many raise questions about the deformities that may occur in human cloning as well, and human cloning raises certain ethical questions. For instance, opponents contend that human clones would effectively have no self-determination because they would be expected to act like their genetic original.