| So just like there are some Mormons who say that Mormon scripture mandates that Mormons should be Transhumanists, there are some Catholics now making what amounts to the same point about Catholic teaching, perhaps even the Vatican itself. I say "what amounts to" because the stated purpose is very different, but the practical meaning, at this point in time, are nevertheless the same.
While Mormon Transhumanists say their scripture calls for developing genetic engineering technology to enhance humanity so that people can become Gods, with immortality and higher intelligence and great strength, the Catholic encyclicals explicitly reject enhancement of natural human abilities precisely because it is attempting to become like God. But they do say that "therapeutic" genetic engineering which seeks only to correct genetic defects that cause diseases is licit, with the huge caveats that it has to be safe and not replace sexual intercourse. Presumably they envision some way to replace the person's own sperm or eggs in their testicles or ovaries with gametes derived from their stem cells that have been modified to fix their bad genes, so they still have sex and the fertilization takes place in the womb and no extra embryos are created. Because that currently is not feasible, the Vatican instructs that germline genetic engineering is currently illicit, "at the present state of research."
The moral evaluation of germ line cell therapy is different. Whatever genetic modifications are effected on the germ cells of a person will be transmitted to any potential offspring. Because the risks connected to any genetic manipulation are considerable and as yet not fully controllable, in the present state of research, it is not morally permissible to act in a way that may cause possible harm to the resulting progeny. In the hypothesis of gene therapy on the embryo, it needs to be added that this only takes place in the context of in vitro fertilization and thus runs up against all the ethical objections to such procedures. For these reasons, therefore, it must be stated that, in its current state, germ line cell therapy in all its forms is morally illicit.
According to the Rebecca Taylor, a Catholic bioethics blogger, that distinction between therapy to make people normal and enhancement to make people better than normal is the difference between good old medicine and bad Transhumanism. But I disagree, I think it is still every bit as Transhumanist to enable people to reproduce with better genes than they would if they did it naturally. Being enabled to reproduce with better genes than we were born with is itself a major enhancement, even if the intent is just to avoid a terrible disorder in one's offspring. And there are still a host of moral and ethical problems that arise. The two issues that the Vatican cares about (no extra embryos created, and the egg and sperm joining by unitive sexual intercourse) don't really seem all that important compared to the other problems that still exist, such as the difficulties of holding the line on what is fixing a defect and what is enhancement, and coercing everyone into having their gametes screened and improved by labs according to their idea of what is normal. In fact, John Paul II had already admonished people about the effect of trying "to prevent the birth of children affected by various types of anomalies. Such an attitude is shameful and utterly reprehensible, since it presumes to measure the value of a human life only within the parameters of "normality" and physical well-being, thus opening the way to legitimizing infanticide and euthanasia as well." It also leads to the belief that people with genetic issues don't have a right to reproduce, and that marriages don't have a right to reproduce with each other's sperm and eggs. That might be why Catholics don't like my Compromise proposal, because it says that marriages have a right to conceive offspring, and Catholics perhaps feel that if the couple has a defect, then they should not be allowed to reproduce.
I think this might explain why some Mormons and Catholics have taken charge of the marriage debate: because they have an ulterior motive to separate marriage from procreation rights, and they both want to society to pursue genetic engineering of healthier people. The people running the show are Transhumanists, and aren't interested in preserving marriage at all.