The United Kingdom Human Fertilisation and Embryology Authority has been in the news for giving the go-ahead to creating three-genetic-parent human embryos.

An embryo has two types of DNA: central nucleus DNA inherited from both its mother and father, and mitochondrial DNA (mDNA) inherited only from its mother. This mDNA can be defective in that it carries genes for serious diseases, such as muscular dystrophy, or it cannot sustain the life of the cells it powers. The three-genetic-parent embryos would have a central nucleus with DNA from its intended mother’s ovum and father’s sperm, and mitochondrial DNA from another woman’s ovum.

The procedure involves creating an embryo from the intended mother’s ovum and father’s sperm, removing the nuclear DNA from the second woman’s ovum leaving behind the mDNA, and transferring the embryo’s central nuclear DNA to the enucleated ovum. The goal is to allow a woman with defective mDNA to have a baby who will inherit most of her genes, but not the defective mDNA.

Is using this procedure ethical?

As always with such issues, the language we choose can affect how we see the ethics of what we are doing. For instance, if we speak of “mitochondrial DNA replacement therapy,” we might see no reason to be alarmed; indeed, we might regard it as a welcome development in treating serious disease. We might make an analogy to other lifesaving transplants, such as heart transplants, and argue there are no ethically relevant differences.

But replacing mDNA is to intentionally alter the human germline, the genes passed on from generation to generation — all descendants of the altered embryo, down the generations, will inherit that alteration. Up to the present there has been an international consensus that we must not intervene to change the human germline, that it must be held on trust as the common heritage of humankind, no matter how much good we believed we could do by altering it.

Marcy Darnovsky, the executive director of the Center for Genetics and Society in Berkeley, California, in the July 9 issue of Nature, explains it this way:

“Mitochondrial-replacement procedures would constitute germline modification. Were the United Kingdom to grant a regulatory go-ahead, it would unilaterally cross a legal and ethical line on this issue that has been observed by the entire international community. This consensus holds that genetic-engineering tools may be applied, with appropriate care and safeguards, to treat an individual’s medical condition, but should not be used to modify gametes or early embryos and so manipulate the characteristics of future children.”

This consensus is reflected in the Canadian Assisted Human Reproduction Act 2004. It prohibits, with heavy criminal penalties for breach, “alter(ing) the genome of a cell of a human being or in vitro embryo such that the alteration is capable of being transmitted to descendants.”

And the transplant of organs is not a viable analogy. Transplanted organs repair a malfunctioning of our body, but are extrinsic to the essence of our very self; altering our foundational DNA modifies the very essence of our intrinsic being, the self itself.

German philosopher Jürgen Habermas writes that doing this would negate two very important values: equality, because designed persons are not equal to their designers; and liberty, because designed persons are not free in their innate being to create their very selves without interference from another person, as this requires that they have non-contingent origins.

I suggest it would also adversely affect and undermine democracy and democratic institutions, since participation in the democratic process is posited on the concepts that we are all equal and all free. The possible consequences are, indeed, frightening.

For such reasons, a principle-based ethics approach would hold that creating three-genetic-parent embryos is inherently wrong and, therefore, must never be undertaken, no matter how much good we might hope to do. But, even if we don’t agree with that and take a utilitarian ethics approach — that is, work from a basis that ethics requires that the benefits must clearly outweigh the risk and harms — we should not proceed with this technology.

The first reason is a pragmatic one that we cannot know the consequences for the person who is “made” in this way and this makes it unethical to use this technology. Proponents of the technology argue that there is only a very small amount of mDNA compared with the total DNA the person inherits and, therefore, it should not raise concerns, in particular, about affecting the person’s identity. But, as Darnovsky explains in the article in Nature, this “is scientifically dubious. The genes involved have pervasive effects on development and metabolism.” She concludes that although “proof of safety is, by definition, impossible in this situation, the evidence submitted up to now on mitochondrial replacement is far from reassuring.”

Even more importantly, creating three-genetic-parent embryos would be to cross a line-in-the-sand and open up a precedent for constructing “designer babies” and cloning — the latter involves the same techniques as three-genetic-parent babies.

My use of the word constructing is not accidental: “building better babies” with reproductive technologies is the 21st Century’s eugenics. We can compare doing this with the approach of the philosopher, the late Hans Jonas, who believed that every person had a right to their own unique ticket in the great genetic lottery of the passing on of human life.

We should reject “genetic reductionism,” which postulates that we are nothing more than a product of our DNA, but our inherited DNA is, nevertheless, an intrinsic part of who we are and requires special respect.

There is a difference in kind between designing the essence of a human being and treating a person with a genetic disease with somatic cell DNA therapy. The latter is analogous to other medical treatments, does not alter the essence of the person, and does not involve inheritable changes. Used appropriately, especially with full regard to safety concerns, it is ethical. Altering the human germline, which making three-genetic-parent embryos involves, no matter how much good we hope to do is, in my opinion, not ethical.

Margaret Somerville is director of the McGill Centre for Medicine, Ethics and Law.

Margaret Somerville is Professor of Bioethics at the University of Notre Dame Australia School of Medicine (Sydney campus). She is also Samuel Gale Professor of Law Emerita, Professor Emerita in the Faculty...