The possibility of editing the genome of living beings is set to revolutionize many areas of biological research. For the first time, scientists can now efficiently, precisely, and selectively edit parts of these genomes by removing or inserting genetic material.
This is especially the case with the CRISPR-Cas9 editing system which is relatively easy and inexpensive to use while only requiring two components to work. These components are a guide RNA genetic sequence (a kind of a homing mechanism) and a Cas enzyme (a protein that works as a sort of molecular scissors), with Cas9 being the enzyme that is most used to cut the DNA strands.
In this way, the guide RNA with a certain genetic code seeks out the specific genetic target of the DNA strand of the genome and then forms a complex with the Cas9 enzyme. This cleaves the DNA strand and enables a specific genetic sequence to be taken out. The strand can then be rejoined or, alternatively, a new genetic sequence inserted.
As a result, gene editing can be used in research with, for example, specific gene sequences being disabled or replaced in early animal embryos in order to better understand embryonic development. In addition, it is suggested that it will be possible, in the future, to inactivate disordered genes which may be responsible for a disease and replace them with healthy ones. The prevention of genetic disorders and even new treatments could then be considered.
Biomedical trials using gene editing on human cells are already underway, such as in the use of edited immune cells to treat cancer. But two important milestones were achieved when Chinese scientists became the first to gene edit a human embryo in 2015 and bring to birth twin girls who were gene edited as single cell fertilised eggs in 2018. Other studies have also been reported using either existing human embryos and genetically editing them after fertilization (post-conception) or injecting the gene editing system at the same time as fertilization (peri-conception). A third possibility would be to edit the genes of the sperm or egg cell before conception (pre-conception). In these last two procedures, it is expected that the embryo would develop in such a way that every cell, and every subsequent organ, would contain the edited DNA, including the reproductive cells, enabling a more efficient, uniform gene editing to take place in the individual.
In the UK, all these different kinds of gene editing procedures in human embryos were approved by the Human Fertilisation and Embryology Authority in 2016, but only for research embryos which are not intended to be used for reproductive purposes.
From an ethical perspective, some general comments have already been expressed elsewhere highlighting the many advantages and benefits to humankind arising from the possibility of manipulating the genes of possible future or existing persons.
However, some concerns relating to safety exist. For example, inserting or deleting specific genes in the correct location of the genome of a developing embryo without upsetting the biological equilibrium of the cell(s) is a difficult operation. A particular gene may influence a number of different characteristics which means that even if a gene was modified to influence a specific dysfunction, this could give rise to unexpected consequences. The overall result would be a modification that may be less than beneficial.
In addition, during the research and development stages of human embryonic gene editing it is unavoidable that a significant number of embryos will be destroyed in the process. Since such embryos may be considered as full persons, made in the image of God, this means that their destruction can be seen, by many, as being just as offensive and immoral as the destruction of any other person.
Another ethical concern is that, if the gene editing is inheritable, it would alter the genetic makeup of an individual’s children and future generations, which may have unforeseeable effects. Moreover, if it is eventually possible to alter a person’s genes and those of his or her descendants to remove or change attributes such as predisposition to disorders, it may also be possible to change just about any other attribute.
Because of this, grave concerns have been expressed as to the consequences for society when it becomes possible to decide what kinds of children are brought into existence. Ever since the English writer and philosopher Aldous Huxley published his science fiction book Brave New World in 1932, considerable anxiety has existed relating to the prospect of creating a society in which the genetic heritage of individuals could be manipulated. In this regard, though the book was set in the year 2540, gene editing has brought Huxley’s dystopian future a whole lot closer, meaning that the ethical implications of such a world now need to be considered.
To do this, more specific ethical issues concerning gene editing must be examined relating to the extent of the changes being contemplated, and these will be examined in turn. But before doing this it is necessary to examine the different kinds of personal identities that may exist in order to make a difference between procedures which are either therapeutic and those which actually create a new individual who is different to the one who would otherwise have existed.
In discussing the concept of identities, it is important to first emphasise the various ways in which identity can be distinguished. Though a degree of overlap may exist, and there is no consensus in literature, it is possible to differentiate between:
- A biological perspective which reflects the continuous biological being remaining one and the same whole being over time as a biological entity in space despite some qualitative changes such as those arising from the replication and division of cells making up this being.
- A psychological or biographical perspective which reflects the relationship a living being has to itself as remaining one and the same whole individual over time despite some qualitative changes. This generally includes continuity of consciousness, experiential contents or the maintaining of psychological connections or capacities, such as memories.
On this account, a psychosomatic numerical identity would exist for most individuals which brings together the biological and psychological perspectives.
This means that if a procedure results in numerical identity changes, then a new individual is brought into existence who would not otherwise have existed. On the other hand, if a procedure results in qualitative identity changes, then the original individual continues to exist.
To begin with, if the editing takes place with the aim of addressing a genetic disorder on a mature embryo, foetus, child, or adult, this could be considered in a similar manner to already existing somatic gene therapy procedures which do not affect descendants and have generally been accepted by society. This form of therapy would then correspond to the aims of classical medicine in the restoration of health to the patient. As the Christian physician and ethicist John Wyatt indicates: “the task of the health professionals is to protect and restore the masterpieces [of human bodies] entrusted to [their] care, in line with the original creator’s intentions.”
Such applications of gene editing for therapeutic purposes, therefore, would not raise many new significant ethical problems, apart from safety and efficacy. The numerical identity would remain the same though the qualitative identity would be changed.
Using gene editing with the aim of germline gene modifications (intentionally changing the genes of children and descendants), on the other hand, raises significant ethical concerns. This is because proposed germline modifications are inherently eugenic in nature. The word eugenics, which derives from two Greek roots “eu” (good) and “genesis” (birth), describes selection strategies or decisions aimed at affecting, in ways which are considered to be positive, the genetic heritage of a child, a community, or humanity in general.
It was the Englishman Sir Francis Galton who first coined the term eugenics in 1883 as he sought to implement into human beings selection procedures for inherited characteristics which had already been used, with success, in animal breeding programs.
At the beginning of the 20th century, eugenic ideas were actually being considered by many prominent personalities. Sir Winston Churchill, wartime Prime Minister of the UK, was openly disappointed when Britain resisted eugenic action on the grounds of civil liberties. In 1910, he wrote to the then UK Prime Minister expressing his support for legislation that proposed to introduce a compulsory sterilization program in the UK saying:
The unnatural and increasingly rapid growth of the feeble-minded and insane classes, coupled as it is with a steady restriction among all the thrifty, energetic and superior stocks, constitutes a national and race danger which it is impossible to exaggerate. . . . I feel that the source from which the stream of madness is fed should be cut off and sealed up before another year has passed.
It was only because a deep reaction of aversion took place towards the atrocities implemented by Nazi Germany during World War II that eugenic ideology was discarded. A number of international legal texts condemned the ideology, including the United Nations Educational, Scientific and Cultural Organization’s (UNESCO) 1997 Universal Declaration on the Human Genome and Human Rights which indicates in Article 24 that germline interventions could be considered as a practice that would be “contrary to human dignity.” Additionally, the Council of Europe’s 1997 Convention on Human Rights and Biomedicine states in Article 13, regarding “interventions on the human genome,” that “an intervention seeking to modify the human genome may only be undertaken for preventive, diagnostic or therapeutic purposes and only if its aim is not to introduce any modification in the genome of any descendants.”
This means, according to paragraph 91 of the Explanatory Report to this Convention, that “interventions seeking to introduce any modification in the genome of any descendants are prohibited. Consequently, in particular genetic modifications of spermatozoa or ova for fertilisation are not allowed.”
The reasons why such texts rejected germline modifications, and thereby eugenic procedures, was because unacceptable discrimination is inevitably associated with selection strategies, thereby undermining the equality in worth and value of all human beings—an equality which is the very basis of civilized society. Thus, deliberate germline and eugenic procedures were not only seen as wrong because a degree of coercion existed in some of the past reproductive practices, but also because they undermined the very basis of equality between all existing or possible future persons.
But, as the abuses which took place in the first half of the 20th century slowly become an ever older memory, pressures are now returning for a new eugenics. For example, American Nobel Prize Laureate and co-discoverer of the structure of the DNA molecule James Watson wrote in 1995:
But diabolical as Hitler was, and I don’t want to minimize the evil he perpetuated using false genetic arguments, we should not be held in hostage to his awful past. For the genetic dice will continue to inflict cruel fates on all too many individuals and their families who do not deserve this damnation. Decency demands that someone must rescue them from genetic hells. If we don’t play God, who will?
Moreover, in a report published in 2017, the U.S. National Academies of Sciences, Engineering, and Medicine actually recommended the use of germline gene editing in human beings in certain specific circumstances. This happened even though the above international regulations had previously condemned such a possibility and a 2015 UNESCO International Bioethics Committee report had clearly highlighted the eugenic dangers of germline procedures. This indicated that if any intentional germline selection was accepted (such as with gene editing), this would “jeopardize the inherent and therefore equal dignity of all human beings and renew eugenics, disguised as the fulfilment of the wish for a better, improved life.”
Indeed, it was in order to address such a danger that Article 3 of the EU Charter of Fundamental Rights was drafted in 2000, which explicitly states that “in the fields of medicine and biology . . . the prohibition of eugenic practices, in particular those aiming at the selection of persons” must be respected.
At this stage, however, it is important to examine which gene editing procedures could be considered as eugenic. This is because there may be distinct categories dependent upon the stage of development at which the editing is being considered.
If gene editing takes place on a very early post-conception human embryo (such as a two-cell embryo), a number of ethical challenges arise. Indeed, it would be difficult to know whether any significant genetic change would bring about a completely new individual or whether the original embryonic individual continues to exist and is simply modified. In other words, whether the procedure would have a numerical or only a qualitative effect on identity.
In a way, this philosophical conundrum is not new and comes in many different forms. It is similar to the one mentioned by the Greek historian Plutarch (c. 46–120) in his Life of Theseus (the mythical founder-king of Athens). In this, Plutarch questions in a thought experiment whether a ship which is restored by replacing every one of its wooden parts remains the same ship. This is especially relevant if the old parts are then used to build another ship. In the same way, it is possible to ask whether an embryo in which a certain number of genes have been edited remains the same embryo or whether a change in numerical identity has taken place.
From an ethical perspective, if the genetic modification does not give rise to any significant change in the already existing embryo, it would no doubt be seen as similar to somatic gene therapy in which the original individual remains and the masterpiece is restored.
However, if the gene editing procedure substantially modifies the genome of a very early embryo, more questions relating to the continued existence of the original embryonic individual could be asked. Genetic modification may then be considered to end the life of the original embryo (a form of death) while creating another. Indeed, if this did happen, then a clear eugenic element would exist since it would mean preferring one new being over another based on the quality of his or her genome.
On the other hand, if a genetic modification takes place either on the sperm and egg cells before they are used for conception or during fertilisation resulting in the formation of a one-cell embryo, a new individual, who would not otherwise have existed, is being brought into being. This would happen because any change (no matter how small) of any of the variables in bringing an individual into existence would result in a very different individual existing in time. In other words, any individual brought into existence through these procedures would be a totally different person, from a numerical identity perspective, to the one who would, otherwise, have existed.
If such a conclusion is accepted then this again has a clear eugenic element since a new individual is being brought into existence in preference to another who may, for example, have qualities which were seen as less valuable than the ‘new’ individual. What is being proposed, therefore, is not a form of therapy. No existing person is being treated for a disorder. Instead, it is making sure that only certain persons are brought into existence based on the quality of their genomes.
Of course, it is possible to ask what is ethically wrong in deciding to make sure that only healthy, and not disabled, children are brought into existence. Why not make sure that children who will have a short and difficult life of suffering are not brought into existence?
In response to these questions, it is important to recognize that it is difficult to see how parents can decide not to have certain kinds of children without making a value judgement that some children are less desirable. It follows that when parents make a decision that only a certain kind of child should be brought into existence, based solely on genetics factors, this can only mean making a eugenic choice and preferring one possible future child over another. In other words, this decision contradicts the important principle that the lives of all human beings have the same worth and value, regardless of their state of health or characteristics.
From a Christian perspective this is very important since the inherent and equal value of each human life is based on the reality that every human being is created in the image of God and is called to a future eternal destiny with him. Thus, from God’s perspective, every person has the same value and worth no matter how long or short a person lives, no matter how self-aware he or she is, and no matter how much suffering or pleasure this person experiences during life on earth. As John Wyatt explains, “our creation in God’s image implies . . . a radical equality. . . . In the human community, we are surrounded by other reflections of God who are different but fundamentally equal in dignity to ourselves.”
This radical equality of human beings, which exists because they all reflect the image of God, also resonates in Article 1 of the UN’s 1948 Universal Declaration of Human Rights which states that “all human beings are born free and equal in dignity.” Thus, if all persons are equal in value and worth, how can a choice between two supposedly equal future persons ever be made?
It is possible to argue, as does the 2017 U.S. report Human Genome Editing, that “unconditional love for a disabled child once born and respect for all people who are born with or who develop disabilities are not incompatible with intervening to avert disease and disability prior to birth or conception.” But the report does not explain how or why any deliberate discrimination can be seen as acceptable before birth while suddenly becoming unacceptable after birth. As Hans Reinders explains, it is more than likely that “in any given case, the only reasonable answer to the question of why a disabled child should not be born is by reference to what one thinks about the lives of people living with the same disorder.”
In other words, if parents do decide to avoid having a child affected by a serious genetic disorder, based solely on genetics factors, there is a very real sense that such a decision is based on the perceived quality of life of people who already exist and not on the worthiness and inherent dignity of their lives. Moreover, the indirect message being given to persons, who have already been born with the same disorder, would be that they should also not have existed. This is clearly discriminatory and would undermine the inherent equality of all human persons in society.
Suggesting that choice should be available to make sure that certain kinds of children are not brought into existence may also mean that there is such as thing as a “life unworthy of life” in society. As Roberto Andorno explains:
In reality eugenic ideology presupposes stepping from a “worthiness of life” culture to a “quality of life” culture, in other words, to the idea that not every life is worthy of being lived, or to put it more bluntly, that there are some lives that do not have any worth.
In a Christian understanding of procreation, moreover, the unconditional and sacrificial love of the parents towards each other and towards God should also expand onto the child. This means that every child brought into existence from this love should, in the same way, be unconditionally loved and accepted by his or her parents.
However, if certain genetic preconditions are laid down relating to the procreation of a possible future child—thus excluding persons with certain conditions, then this can no longer reflect the Christian basis of unconditional procreative love. Moreover, this child when brought into existence will always know that his or her very existence was not unconditional but conditional on having certain genes which may give rise to very significant existential anxiety.
Naturally, it is difficult not to have a lot of sympathy towards parents who have children affected by severe disability and suffering or to know the extent of the anguish they are going through. But, if one asks these parents, it is always the disorder and not the very existence of the child with the disorder that has been the cause of so much heartache. Most would never say that they wished their specific child had not existed. On no occasion, would they indicate that they would have preferred to exchange their child for another, healthier, one. They just want to find a treatment for their child.
Certainly, the advancement of autonomy, the reduction of suffering, and the increase in flourishing of human persons are very important goals in any Christian ethical appraisal. But these aims do not give any true value or worth to human life, at least not the kind of value and worth that is equal to all persons. In actual fact, if only autonomy or the lack of suffering were the basis of the value and worth of an existing or possible future person, then every human being could be classified on a scale—classified as having a different value and worth. This would then come into opposition with the very concept of an egalitarian and civilized society.
It is, thus, imperative for Christians to always be prepared to equally value, without selection and preconditions, each and every human individual. In the same way, it is the reason why a Christian civilized society must welcome into existence all possible future persons independently of their biological or other characteristics such as their genetic qualities or disorders.
Of course, it is possible to challenge this statement by emphasising that certain forms of prenatal selection are already taking place, including in preimplantation genetic selection, whereby, following IVF, only the ‘best’ embryos are selected for implantation. Moreover, it can be argued that such procedures have not given rise to any perceived damage to the equality between persons. But these procedures are, in effect, already sending the message that all persons are not equal in value and worth and that some should not be brought into existence. And the more the vulnerable edifice of equality in civilized society is undermined by decisions that weaken its very foundations, the more likely it is that this equality may eventually disappear.
In conclusion, gene editing can be used in a very positive medical manner in helping to restore the masterpiece of human bodies. This would then be comparable to other somatic gene therapy procedures already in existence which should be welcomed.
But, at the same time, society is now before a crossroads with germline genome editing and some forms of prenatal selection procedures. It can either choose to make sure that certain persons are not brought into existence because the value of their lives is considered to be unacceptable. This would then mean that society would begin to classify the worth of all lives and start going down a eugenic road. Or, it can choose to believe that all lives are equal in worth and value, making any selection and classification meaningless, which is the very basis of civilized Christian society.
God will never prefer some persons over others no matter how able or disabled they may be or how much pleasure or suffering they experience during their lives. Instead, each one will be created with his amazing image expressing the wonderful, immeasurable and unconditional love which exists in God.
Note: The views expressed in this article are those of the author and do not necessarily reflect the positions of the professional organisations with which he is affiliated.
 Le Cong et al., “Multiplex Genome Engineering Using CRISPR/Cas Systems,” Science 339, no. 6121 (2013): 819–823; Martin Jinek et al, “A Programmable Dual-RNA-Guided DNA Endonuclease in Adaptive Bacterial Immunity,” Science 337, no. 6096 (2012):816–821.
 Clustered regularly-interspaced short palindromic repeats with the Cas9 protein, i.e., the CRISPR-Cas9 system.
 Daryl F. Sas and Hannah Martin Lawrenz, “CRISPR-Cas9: The Latest Fashion in Designer Babies,” Ethics & Medicine 33, no. 2 (2017): 85.
 Nerges Winblad and Fredrik Lanner, “Biotechnology: At the Heart of Gene Edits in Human Embryos,” Nature 548, no. 7668 (2017): 398–400, doi:10.1038/nature23533.
 Puping Liang et al., “CRISPR/Cas9-Mediated Gene Editing in Human Tripronuclear Zygotes,” Protein Cell 6, no. 5 (2015): 363–372.
 David Cyranoski and Heidi Ledford, “Genome-Edited Baby Claim Provokes International Outcry,” Nature 563 (2018): 607–608.
 Ibid.; Xiangjin Kang et al., “Introducing Precise Genetic Modifications into Human 3PN Embryos by CRISPR/Cas-Mediated Genome Editing,” Journal of Assisted Reproduction & Genetics 33, no. 5(2016): 581–588; Lichun Tang et al., “CRISPR/Cas9-Mediated Gene Editing in Human Zygotes Using Cas9 Protein,” Molecular Genetics and Genomics,” 292, no. 3 (2017): 525–533.
 Hong Ma et al., “Correction of a Pathogenic Gene Mutation in Human Embryos,” Nature 548, no. 7668 (2017): 413–419, doi:10.1038/nature23305.
 National Academies of Sciences, Engineering, and Medicine, Human Genome Editing: Science, Ethics, and Governance (Washington D.C.: The National Academies Press, 2017), https://doi.org/10.17226/24623; and Nuffield Council on Bioethics, Genome Editing and Human Reproduction: Social and Ethical Issues, (London: Nuffield Council on Bioethics, 2018), http://nuffieldbioethics.org/wp-content/uploads/Genome-editing-and-human-reproduction-FINAL-website.pdf.
 The President’s Council on Bioethics, Beyond Therapy: Biotechnology and the Pursuit of Happiness (Washington, D.C.: The President’s Council on Bioethics, 2003), 38–39.
 Michelle Kirtley, “CRISPR Update: Considerations for a Rapidly Evolving and Transformative Technology,” Dignitas 23, No. 1, (2016): 1, 4–8.
 Calum MacKellar and Christopher Bechtel, The Ethics of the New Eugenics (New York: Berghahn Books, 2014).
 For further discussion see for example Marya Schechtman, The Constitution of Selves (Ithaca, NY: Cornell University Press, 1996); Maartje Schermer, “Ethical Issues in Deep Brain Stimulation,” Frontiers in Integrative Neuroscience 5, no. 17 (2011), doi: https://doi.org/10.3389/fnint.2011.00017; Foresight Future Identities, Future Identities: Changing Identities in the UK—The Next 10 Years, Final Project Report (London: The Government Office for Science, 2013), 9–10; and David DeGrazia, Creation Ethics: Reproduction, Genetics, and Quality of Life (Oxford: Oxford University Press, 2012), 70–73.
 This reflects an ‘animalism’ perspective which was coined by Paul F. Snowdon, see Paul F. Snowdon, Persons, Animals, Ourselves (Oxford: Oxford University Press, 2014). For a further discussion see Eric T. Olson, “An Argument for Animalism,” in Personal Identity, ed. Raymond Martin and John Barresi (Oxford: Blackwell, 2003), 318–334.
 This reflects a ‘psychologically interconnected’ perspective. See for example David Lewis, “Survival and Identity,” in The Identities of Persons, ed. Amelie Oksenberg Rorty (London: University of California Press, 1976), 17–41. Such a psychological interconnection would not exist, for example, between an early embryo and an adult human being since the latter would not be able to remember being an embryo.
 Even conjoined twins can be considered as distinct if they each experience their own specific identity.
 John Wyatt, Matters of Life & Death: Human Dilemmas in the Light of the Christian Faith, rev. ed. (Nottingham: IVP, 2009), 100.
 MacKellar and Bechtel, The Ethics of the New Eugenics.
 Quoted in Amy Iggulden, “The Churchill You Didn’t Know,” The Guardian, November 27, 2002, https://www.theguardian.com/theguardian/2002/nov/28/features11.g21 (accessed October 21, 2018).
 United Nation’s Educational, Scientific, and Cultural Organization (UNESCO), The Universal Declaration on the Human Genome and Human Rights, November 11, 1997, http://portal.unesco.org/en/ev.php-URL_ID=13177&URL_DO=DO_TOPIC&URL_SECTION=201.html (accessed October 21, 2018). The Universal Declaration on the Human Genome and Human Rights was adopted unanimously and by acclamation at UNESCO's 29th General Conference on 11 November 1997. The following year, the United Nations General Assembly endorsed the Declaration.
 Council of Europe, “Convention for the Protection of Human Rights and Dignity of the Human Being with Regard to the Application of Biology and Medicine,” European Treaty Series no. 164, 4.IV (Oviedo, 1997): Article 13, https://rm.coe.int/168007cf98 (accessed October 29, 2018).
 Council of Europe, “Explanatory Report to the Convention for the protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine: Convention on Human Rights and Biomedicine,” European Treaty Series no. 164, 4.IV (Oviedo, 1997): Paragraph 91, https://rm.coe.int/16800ccde5 (accessed October 29, 2018).
 It should be noted that a decision not to have a certain kind of child may also be based on other factors, such as a genuine psychological, financial and material inability by some parents to cope with a very seriously disabled child. Such a decision would not then be eugenic in nature.
 James Watson, “Values from Chicago Upbringing” in Deoxyribonucleic Acid: The Double Helix—Perspective and Prospective at Forty Years, ed. Donald A. Chambers (New York: New York Academy of Science, 1995), 197.
 National Academies of Sciences, Engineering, and Medicine, Human Genome Editing.
 UNESCO International Bioethics Committee, “Report of the IBC on Updating Its Reflection on the Human Genome and Human Rights,” SHS/YES/IBC-22/15/2 REV.2, October 2, 2015, http://unesdoc.unesco.org/images/0023/002332/233258E.pdf (italics original).
 “Charter of Fundamental Rights of the European Union” Official Journal of the European Communities, C 364/1, December 18, 2000, http://www.europarl.europa.eu/charter/pdf/text_en.pdf.
 Pilar N. Ossorio, “Inheritable Genetic Modifications: Do We Owe Them to Our Children?” in Designing Our Descendants: The Promises and Perils of Genetic Modification, ed. Audrey R. Chapman and Mark S. Frankel (Baltimore: Johns Hopkins University, 2003), 259–262.
 Derek Parfit, “Rights, Interests and Possible People,” in Moral Problems in Medicine, ed. Samuek Gorovitz et al. (Englewood Cliffs, NJ: Prentice Hall, 1976), 369–375.
 Roberto Andorno, “Fondements philosophiques et culturels de l’eugénisme sélectif,” in La génétique, au risque de l’eugénisme? ed. Jean Laffitte and Ignacio Carrasco de Paula (Paris: Edifa-Mame, 2010), 129–141.
 James J. Walter, “Theological Parameters: Catholic Doctrine on Abortion in a Pluralistic Society,” in Abortion and Public Policy: An Interdisciplinary Investigation within the Catholic Tradition, ed. Randall R. Rainey and Gerard Magill (Omaha, NB: Creighton University Press, 1996), 100.
 Wyatt, Matters of Life & Death, 61.
 UN General Assembly, Universal Declaration of Human Rights, 217 (III) A (Paris, 1948), Article 1, http://www.un.org/en/universal-declaration-human-rights/ (accessed October 21, 2018).
 National Academies of Sciences, Engineering, and Medicine, Human Genome Editing, 97.
 Hans S. Reinders, The Future of the Disabled in Liberal Society (Indiana: University of Notre Dame Press, 2000), 8.
 For clear evidence of the feeling of offence being taken by persons with disability in such a situation, it is useful to refer to the disability witnesses in the prominent French court case of Nicolas Peruche. Public Hearings of the French Senate on the 18th of December 2001 relating to the jurisprudence of the ‘Perruche’ case.
 The term a “life unworthy of life” (in German “Lebensunwertes Leben”) first occurred in the title of a book by German psychiatrist Alfred Hoche and lawyer Karl Binding, Die Freigabe der Vernichtung Lebensunwerten Lebens, (Leipzig: Verlag von Felix Meiner, 1920).
 Andorno, “Fondements philosophiques et culturels de l’eugénisme sélectif,” 129–141 (my translation).
 Calum MacKellar, The Image of God, Personhood and the Embryo (London: SCM, 2017), 32–50.
Calum MacKellar, “Gene Editing and the New Eugenics,” Dignitas 25, no. 1 (2018): 3–9.