This article is originally published in The Conversation.

In November of 2018, the Chinese researcher He Jiankui announced the births of twins Lulu and Nana, the first human beings to be genetically modified in their embryonic state. The profoundly unethical manner in which his experiment was conducted led to strong condemnation at all levels.

This terrible situation should not lead us to forget that the possibility of modifying genes, in humans or other living beings, is an enormous achievement. If we manage to control the dysfunctions that are still exhibited by the CRISPR genetic editing technique, we will be able to intervene in the gestation of living beings, develop new treatments, and improve the precision of drugs.

The readers will probably think that things cannot be that simple, that every human achievement usually has some dark side, and that there are always reasons to forgo too much optimism. If so, they are correct. The few years that have passed have shown that we have reasons to be cautious.

First, there are still many things to be improved to ensure the safe use of the technique. However, the scientific obstacles, with all their importance, pale in comparison to the ethical, social, and legal challenges we face. There can be no delay in addressing these challenges because He's reprehensible behaviour has overturned many of the old ethical consensuses about the impossibility of altering the genomes of our descendants. There are already several initiatives to encourage these practices, and we need to react to these initiatives in one manner or another.

Is it not immoral to move towards this future without a well-informed public debate? In my opinion, it is, of course, immoral. Only society as a whole is entitled to make decisions on these issues. Obviously, to make such decisions, there is a great need for improvement in the transmission of available information so that we can all understand what is at stake. This text is intended to contribute to this task. To make the facts more understandable, this exposition is articulated around four basic questions with four answers that can at least clarify why there are no magic solutions to this debate.

Do all forms of genetic modification pose the same ethical and legal challenges?

Fortunately, no. There is a general consensus that the factors that pose specific problems are interventions aimed at modifying the genomes of our descendants. Those interventions that only cause alterations in the genomes of the subjects on whom they are practiced are less controversial because, for better or worse, such changes will disappear with those subjects.

The scenario becomes complex if we think of modifications that are transmitted to future generations. Many see this as posing serious problems because such transmission gives parents almost unlimited power to decide what their offspring will be like, which is morally unacceptable.

I disagree with this argument. In my opinion, this objection ignores the fact that this power already exists. Not exercising it will not make it disappear nor will it absolve us of responsibility because not acting can be as outrageous as exercising this power. Thus, for example, not changing a gene that will cause Tay-Sachs disease is almost as morally reprehensible as introducing a modification that leads to the same result.

The question, in my view, is not whether or not to act or whether or not to alter the genomes of our descendants but when and under what circumstances to do so. Action and inaction can bestow equal guilt.

Are all ends equally legitimate?

Here, the debate is intense. Many voices urge that differences be drawn between therapeutic use and the application of this technology for enhancement purposes (the latter term is used to avoid the term eugenic and its dark connotations). The problem with this recommendation is that it is not easy to draw a clear line between the two concepts.

We all understand that altering a gene that causes a monogenic disease is therapy and that altering our children to have blue eyes is an improvement, but there are many greys between these whites and blacks. Suppose that an embryo has a high probability of developing cancer throughout its life as a person. Let us think that we act to modify the involved genes to make their expressions healthier. Is this a therapy or an enhancement? The answer is difficult to elucidate.

Imagine now that the He experiment works for the circumstances he claims it should. In other words, He’s technique improves resistance to HIV, or further, it is the only or the best method to achieve this. Would this application be a therapy or an improvement? Do the answers remain so simple?

To this conundrum must be added that there are authors who consider that, even if we could draw these distinctions, it would still be unclear why an intervention that seeks to improve our descendants is a moral evil.

The question here, I'm afraid, is how to distinguish between what is an improvement and what is not. Optimising an immune system is probably an improvement. However, is making our offspring 1.90 meters tall also an improvement? Is it really safe to believe that a life would be better for that?

Beyond this difficulty, we should keep in mind that the moment we begin making decisions about goods that (unlike health) are not absolute but are rather comparative (like intelligence), we will have to ask ourselves if we are not excessively invading the autonomies of our children and of others. If we manage to make our offspring gifted, we are at the same time transforming normal children into unintelligent people.

As you can see, the discussion is complex.

Does the adoption of these technologies imply a change in human reproduction?

The answer to this question is inevitably yes. The point is that the use of CRISPR in a reproductive context can contribute to healthier offspring. Not only would this prevent the birth of children affected by serious monogenic diseases—something that is already performed through pre-implantation genetic diagnoses—but it would also increase the likelihood that certain pathologies would not develop or would be successfully dealt with.

The problem is that such interventions would be much more feasible in the early stages of existence, outside the body of a pregnant woman. In other words: modifying genes in embryos will only be possible, at least for a time, with in vitro fertilisation. If this is so, we would have to consider whether using this technology to reproduce ourselves would actually extend into being a moral duty. This duty would be recommended by a general principle of incontrovertible forcefulness that states that we have the obligation to bring our children into this world in the best possible conditions. But is this legitimate and feasible?

Could genetic modification open a gap in our species?

Some opponents of the genetic modification of descendants argue that its application could split humans into two major groups: enhanced and non-enhanced humans.

This split is possible. It is very likely that there would be those who, for ideological or other reasons, refuse to abandon the traditional method of reproduction. Unwanted conceptions would also continue to occur. The fact that these techniques can only be applied via in vitro fertilisation, and the high cost that this entails, would mean that many would not be able to afford these interventions. Of course, differences between countries and continents would also be significant.

Would this gap have a far-reaching effect on our future? It is much more difficult to venture an answer to this question. What is certain is that the accessibility of the techniques and the inequality underlying their absence are among the factors that most strongly favour a delay in their application, except in very specific cases. This delay should be prolonged until this dysfunction can be alleviated or at least until we ensure that the inequalities produced do not go beyond what is bearable.