Today, we have more understanding of our genes than ever before. As a result, we now have the capacity to alter those genes in order to resolve congenital medical conditions – for example, by the use of mitochondrial donation – ‘three-person IVF’ – which was approved earlier this year by parliament. Other techniques that change our germlines – our heritable characteristics – are also on their way, such as the CRISPR/Cas9 technique recently used by Chinese scientists to ‘edit’ the genes of a human embryo. But such developments often inspire resistance – the so-called ‘yuk factor’. In particular, the ability to manipulate our germlines is sometimes described as ‘eugenic’. In order to come to terms with this debate, therefore, we need to understand what eugenics is.

It is no secret that eugenics and genetics are historically connected. In 1883, the word ‘eugenics’ was coined by Francis Galton, a promoter of eugenic policies and a pioneer in the field that subsequently became known as genetics. Ironically, Galton contributed to the discrediting of his own worldview, when genetics ultimately proved that there is no scientific basis for the concept of race.

Nonetheless, the connection between eugenics and genetics remains a source of tension and debate to this day. If eugenics is defined very broadly, as the application of genetics to improve the health of human populations, then it can be made to encompass most if not all of genetics. But the term is often used in a narrower sense, to invoke the horrors of Nazi eugenics programmes during the Second World War. The question of what does and does not constitute eugenics, and when science and medicine should be inhibited because they raise the spectre of eugenics, is often a matter of bitter dispute and no small confusion.

Are we already going too far in our manipulation of human genes, or should we embrace the ability to conquer illness? To what extent should we be concerned about attempts to improve human beings? How should we grasp the nettle of what eugenics is, and whether and in what sense we should find it objectionable?