What are the disadvantages of human cloning?

'Cloning' is the first cousin to 'inbreeding', which ultimately results in a weakened and eventually extinct species.  This is true in dogs, cats, and other mammals.  It might work OK as far as one can tell on the first or second try but pretty soon the undesirable traits will become dominant. 

DNA is the most incredible power that the world has ever seen.  It can and is being used as a tool in safe ways-such as identifying remains of a body, helping to solve crimes, better matching of donors and recipients in transplants,  finding treatments/cures/prevention for genetic diseases, etc.  However, once DNA has been modified ('engineered') and released, it cannot be taken back or undone.  We have seen this with genetically modified crops whose 'modified' DNA has spread to other fields by the wind, birds, bees and other means of transport.

There is at least one documented case in which a boy received a bone marrow transplant from his sister who now exhibits FEMALE DNA.  There is no way to know whether this will affect his ability to live as a man, reproduce, you name it as he was 10 years old when the transplant took place.  So if he commits a crime, shows up as a missing person or anything else that would involve DNA identification, his own DNA will show as a female instead of a male.

This is still brand new, cutting edge, next level Outer Limits stuff where people and other mammals are concerned.  It is not a cure-all and should never be taken lightly nor utilized for frivolous things such as attempting to duplicate one's dead pet.

This is the chain of life on this planet.  It can be studied and used as a gift or as a weapon.  In either case, it MUST be respected for its irreversible and alterring power.

In response to CaptainEricRN and also to clarify my previous post, I would like to make the following comments:

First, my response was to the overall question which asked about human cloning, indicating the cloning of a WHOLE being.  In the wake of the stem cell controversy regarding use of unused embryos and other lifeforms, the discovery that it is possible to utilize a patient's own bone marrow stem cells to replace 'sick' marrow (radiated, then transplanted to 'cure' leukemias) and possibly to grow organs would certainly be of great benefit.

Utilizing a patient's own cells would reduce/eliminate the risk of transplant rejection and the need for immunosuppressant drugs which create their own set of problems.  Surely no one, with the exception of some religious groups, would have a problem with using a patient's OWN cells?

I remain opposed to the transplantation of non-human cells/organs due to the unknown risks of zoonotic syndromes or superinfections.  Many of the brain cell implants have proved to be ultimately ineffective as we saw in Michael J. Fox' case.  I realize that primate hearts and parts have been used successfully for many years but the world is a different place now and there are new animal to human transmissable diseases which have emerged such as influenza strains, 'mad cow' disease, etc.

But, as Capt.Eric pointed out:  all of this is still in the VERY experimental and too early to predict stages.  I remember when the first successful human heart transplant was performed in South Africa and how sensational/exciting that was even though the patient died within a few months.  We may not see results of this research in OUR lifetimes but certainly they may be a very real source of treatment for future generations.

A "cloned" human would be born as an infant like everyone else - I don't think terrorists would create clones and wait until they grow up to use them. They might as well just take small children and brainwash them (whch they do already!).

But it's a good point that some people may look at a cloned person as "inferior," and be prejudiced against them. In reality they would be just like identical twins of the persons they are cloned from.