The human genome consists of twenty-three pairs of chromosomes. These forty-six chromosomes in turn are made up of six billion chemical DNA units called DNA base pairs. Thus, one can visualize a human genome as an encyclopedia of forty-six volumes written with six billion letters.

Thanks to the discovery of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats), we will conceivably be able to open this genetic encyclopedia to any page and edit any single letter. Shortly after CRISPR’s discovery, a cover story in the Economist imagined a society where children are designed so that they are born with perfect pitch, 20/20 vision, no baldness, and decreased risk of Alzheimer’s, breast cancer, and stroke, to name just a few editable features.

What are we to think about the possibility of genetically engineering future generations? As a Catholic priest who is also an MIT-trained molecular biologist and a moral theologian, I have been privy to many conversations among professional ethicists, biologists, and others that have convinced me that the ethical landscape for CRISPR-based technologies can be summarized best by considering three distinctions.

Think here of proposals to design children who are taller, smarter, or more attractive.

First, there is the distinction between therapeutic and non-therapeutic gene editing. Therapeutic interventions delay, prevent, or treat disease and disability. Non-therapeutic interventions, on the other hand, seek to promote some good of the individual other than his or her health and well-being, often seeking to enhance the person’s access to opportunity, privilege, and power. Think here of proposals to design children who are taller, smarter, or more attractive, specifically because it will give them an advantage in life over their non-designed peers.

Secondly, there is the distinction between somatic cell and germline cell gene editing. The former refers to gene editing of any cells in our body other than our egg or sperm cells, while the latter refers to gene editing of these reproductive cells. Significantly, any changes made to the genomes of somatic cells would not be heritable, while changes made to eggs and to sperm would be handed down to future generations.

An example of somatic cell gene editing: Sickle cell disease is caused by a single genetic mutation in the patient’s genome, actually a single alphabet change from an “A” to a “T,” which causes red blood cells to form an abnormal, sickle shape. These sickle cells can clog a patient’s blood vessels, depriving her cells of oxygen, which damages organs, causes severe pain, and often leads to premature death. By correcting the mutation in the blood stem cells back to an “A” and reintroducing these corrected blood stem cells into the patient’s bone marrow, physicians could replace her diseased sickle cells with normal round blood cells, curing her of this debilitating ailment. Notably, however, the patient could still bear children who would suffer from sickle cell disease if they inherit her mutated disease gene, precisely because the genome of her germ cells was not edited.

And finally, there is the concept of dignity. I am often asked what it’s like to debate bioethics in a pluralistic, post-Christian society. I respond by proposing that most disagreements between faith-based bioethicists and their secular counterparts stem from a fundamental disagreement about the nature of human dignity.

Secular ethicists tend to believe that human dignity is only extrinsic, and can therefore be diminished or lost through pain, suffering, or disability. If human dignity can be lost, it follows that we should be able to modify ourselves in ways that we believe would either advance or preserve our dignity. This conception of dignity is the ethical justification given by those who believe that we should be free to design our children so that our species becomes stronger, smarter, more healthy, more attractive, and therefore more dignified.

Secular ethicists tend to believe that human dignity is only extrinsic.

In contrast, faith-based ethicists believe that human beings have dignity that can never be diminished or lost. The Judeo-Christian tradition holds that humans have intrinsic dignity, based on the belief that we are made in the image and likeness of God. This dignity thus cannot be lost, from conception until death, no matter the apparent indignities a person suffers.

It is on this that I base my opposition to non-therapeutic gene editing. Children should be welcomed and not designed..

Recently, for my students here at Providence College, I summarized the technological advances, especially CRISPR, that make designer babies possible. Then I asked: “Would it change things if you discovered that you had been designed by your parents?” One student said that she would always wonder if her parents would still have loved her if she had been the way that she was supposed to have been. Another student added that he would forever worry about falling short of the expectations that his parents had when they designed him, and admitted that he would have resented his parents for this. A third student worried that he would hate his parents for making him something that he did not want to be.

My many conversations have convinced me that the debate over designer babies is not really a debate over the use of CRISPR technology. Rather, it is a debate over how we should understand ourselves and our relationships with others. Designing a child makes his sense of self subject to the whims and fancies of another, and undermines his conviction that he is irreplaceably and individually unique, a gift to be cherished and loved by others. For these reasons – and there are many more – children should be begotten and not made.