This issue is potentially very technical if you don't have a biology background. Everyone knows these days that people have DNA and get some of each from their parents. But the DNA from the mother is actually two separate sorts. This experiment takes one kind from one mother and the other kind from a second mother.

The bottom line is that this is not really like the other gene fixes and transplants; in this case the offspring effectively has three biological parents.

There is nothing obviously wrong with having three biological parents instead of two. But it sure confuses a lot of social conceptions of relationship. And of course, it's not natural at all. I can readily imagine conservatives claiming that God demands that we have one mother and one father, not some other combination, the same way they claim marriage is one man and one woman.

There is also a more difficult to describe potential, well, question. This second kind of DNA from the mother (mitochondrial) never mixes with the father's DNA. It continues in an unchanged line from mother to daughter indefinitely. By deeming some lines inferior because they can cause disease, we are significantly interfering with the human genome. Maybe for the better; but, certainly requiring a very close look.

I think transplantation of DNA needs to be done at cell (egg) level and by the time it becomes and embryo you cant change the DNA that would be like transplanting DNA on a fully grown human would it not?

Actually, the DNA that was transplanted into the embryo was not the normal DNA that we think about every day. This kind of DNA is actually very unique, for it comes only from the mother. If you think about the reproductive process of a female, the egg is formed and then fertilized. The most common misconception is that only the DNA from the egg and the sperm create the baby. Many diseases are actually transmitted from this unique DNA that is found in the mitochondria of the mothers egg.

The ethical debate over this issue stems from the conception that this could be used to cure diseases and in turn create a perfect race.

In my opinion though, this could be used greatly in genetics research and in the field of biology. This could not only be used to teat diseases, but it could also be used to study the nature of them as well. This method of "curing" human disease could prove itself very useful as we combat mitochondrial disease in the future.