The Roman Catholic View
Many Christians believe that it is morally wrong to experiment on human life of any kind. Innocent human life should always be protected. The Roman Catholic Church teacher than an innocent human life comes into existence at the moment of conception. The embryo, as the potential person, will become a person and should therefore be given dignity and respect of a person.
A Catholic natural law tradition, however, does not reject all gene therapy if it is for ‘strictly therapeutic’ reasons and its aim is to ameliorate the genetic disorder providing that is it for the well-being of the person and not for positive or cosmetic reasons. This can be justified as Aquinas’ primary precept is to live.
In Summary, the Catholic position is:
Any form of genetic engineering that involved the use of embryos outside the womb (e.g. embryonic stem cell therapy, cloning) is wrong.
Genetic enhancement is wrong for cosmetic reasons - God creates everyone uniquely.
Gene therapy is acceptable to cure disease, as long as it does not involve any major risks to human life or involved use of spare embryos or embryos outside the womb.
Reproductive cloning is wrong as new life should be created naturally through sexual intercourse.