A three-parent baby or a change of battery? Language in the ethical debate on mitochondrial donation

On 22nd October 2014, the House of Commons Science and Technology committee will hold a one-off evidence session on a new human fertilisation technique variously known as mitochondrial donation, mitochondrial transfer or mitochondrial replacement. This technique is intended to help women who carry serious genetic diseases that are passed to the embryo through the mitochondria – the outer layer of the egg (e.g. muscular dystrophy). In such cases, the cell’s mitochondria would be replaced with mitochondria from a healthy donated egg immediately before or after fertilisation, thus eliminating the possibility that the child will inherit the genetic disease.

The first embryo with donated mitochondria was successfully created at Newcastle University in 2010. In 2012, the Nuffield Council on Bioethics approved the procedure. However, the technique has not yet been legally approved in the UK. Two public consultations have found that the majority of people are in favour of introducing the technique, but have also revealed some opposition. Previous parliamentary discussions have primarily focussed on the safety of the procedure. However, concerns have been expressed both in Parliament and in the media about the ethics of manipulating the genetic make-up of human embryos.

As far as the ethical issues are concerned, the language used to describe the procedure is crucial, especially in media reporting. In order to study this language systematically, we constructed a dataset (corpus) including all relevant news reports published in the UK press between April 2010 (when the Newcastle team announced the success of the technique), and September 2014. The corpus contains a total of 119 news articles, amounting to 64,804 words. We have found that, in our data, the words used to express the case for or against approval frame the issue in opposite and irreconcilable ways. This, we suggest, reduces the chances of a reasoned debate, and makes it difficult to see the merits of the case.

The case in favour: changing a faulty battery

In April 2010, Newcastle University issued a press release in which one of the directors of the research, Professor Doug Turnbull, explains the new procedure as follows:

‘Every cell in our body needs energy to function. This energy is provided by mitochondria, often referred to as the cells’ ‘batteries’. Mitochondria are found in every cell, along with the cell nucleus, which contains the genes that determine our individual characteristics. The information required to create these ‘batteries’ – the mitochondrial DNA – is passed down the maternal line, from mother to child.


“What we’ve done is like changing the battery on a laptop. The energy supply now works properly, but none of the information on the hard drive has been changed,” […] “A child born using this method would have correctly functioning mitochondria, but in every other respect would get all their genetic information from their father and mother.”

The ‘battery metaphor’ is one of the main rhetorical strategies used in our data to suggest that the procedure poses no ethical issues, and should thus be approved on medical grounds: most people can relate to how changing the battery in an appliance does not affect its essential characteristics. The noun battery occurs 38 times in the data, including both the singular and plural forms. We used a new software tool to find the top ‘collocates’ of the singular form battery, i.e. the words that are strongly associated with this word in our corpus. This tool displays collocates as a network with the search word in the centre (see figure 1).


Figure 1 – Collocation network for battery

Battery is closely linked with the technical term mitochondria on the one hand, and, on the other hand, with a small set of words that belong to the ‘battery’ metaphorical scenario: pack, faulty, replacing and changing. The extracts below are instances of the pattern displayed in figure 2:

About one in 6,500 children are born with defects in their mitochondria – the “batteries“ that power each cell.

The new techniques would see defects in a cell’s battery pack, the mitochondria, replaced by a healthy version supplied by a woman donor

[Mitochondria] are like batteries in a camera or a laptop – you can change them without changing anything else. The child’s identity will come from its two parents, who determine the nuclear DNA.

In these extracts, the focus is on the way in which serious medical problems can be avoided by means of an intervention at the level of cells.

The case against: three-parent babies

The case against approval focuses on the babies who would be born as a result of the procedure, and particularly on their kinship relationships with the people whose cells would be involved in the creation of the embryo: the woman who carries the genetic disease, the woman who donates the healthy mitochondria, and the man whose sperm is used to fertilise the egg.

The word baby as a singular noun occurs 99 times in the corpus, and the plural form babies occurs 268 times. Figure 2 shows the network of words that centres around the plural form babies in our corpus.


Figure 2 – Collocation network for babies

As figure 2 shows, the collocates of babies include:

  • Words that relate to the debate, and to the issue of official approval: approve, legalise, draft, sanction, permit, backing, comment, ministers.
  • Words that relate to the procedure itself and its outcome: create, created, creation, order, genetically, modified, GM, designer, eugenics, three, three-parent.

The second group in particular reveals the main argument against approval of the procedure, namely that it involves the creation of genetically modified babies with three biological parents. This, it is argued, would pave the way to a future where prospective parents can choose the characteristics of their children, such as eye colour. The following extracts express this position:

Three-parent babies may never know their ‘second’ mother

Government accused of dishonesty over GM babies

Dr David King, of watchdog Human Genetics Alert, said: “This will eventually lead to a designer baby market. […]”

Done differently, it could lead to the creation of designer babies , made to order by hair colour or eye colour.

More specifically, the corpus contains 40 instances of three-parent baby/babies, 33 instances of designer baby/babies and 12 instances of GM babies. In some articles, these phrases are used to place mitochondrial donation alongside other ethically controversial issues:

Issues ranging from fracking to three-parent babies and genetically modified crops are all difficult […].

The problem with the two alternative linguistic framings

The cases for and against approval or mitochondrial donation are expressed in the press in ways that polarise the issue in an extreme, and arguably unhelpful, fashion. In the case against, the creation of a human baby from the genetic material of three people results in a genetically modified, designer human being, and in an abnormal kinship relationship involving two mothers and three parents. In the case in favour, the use of mitochondria from a donated egg is a mechanical process that has negligible genetic implications and no abnormal kinship implications at all. More generally, the case against focuses on the people involved in the process and their relationships, while the case in favour focuses on what scientists do in a lab in order to prevent serious incurable conditions. As figures 1 and 2 show, the two networks centering on babies and battery do not meet: they have no words in common. For example, the verb form associated with the battery network is replace, whereas for babies it is create.

In this context, it is difficult for non-experts to make sense of the complex scientific issue that underlies the ethical questions, namely the function of mitochondria and their role in the genetic make-up of human beings. Those who adopt the ‘battery metaphor’ tend to point out that mitochondria only provide 0.1% of a human being’s genetic material, none of which influences the characteristics that we associate with identity and uniqueness. Those who adopt the ‘three-parent’ view implicitly suggest that two women are equally involved in the creation of the embryo, presumably because the provision of any amount of genetic material would constitute biological parenting.

The language used in the media to represent both sides over-simplifies and polarises the issue, and therefore makes it difficult to understand the basis of the disagreement. It would be desirable to have a debate that enables the public to appreciate the nature and complexity of the scientific issues, so that they can form a reasoned view of the implications of the introduction of the procedure. To achieve that, both sides have to abandon the current linguistic framings, and find a common linguistic ground from which to argue their respective cases.