Genetics has revolutionised not just how we think of biology but how we think of ourselves. We are, in the words of one geneticist, the first organism that has ‘learned to read its own instructions’. Now, with the breakthrough of gene-editing technology — whose precision allows us to alter a single letter of DNA — we can now not only decipher but rewrite our genetic code. We may soon be able to treat diseases such as cancer not simply with drugs, but with genetic manipulation. Yet behind this medical revolution lies the prospect of something altogether more worrying. Already, we possess the technology to add to our genetic code at will, and thus create the world’s first generation of ‘transgenic’ humans. As we intervene genetically on ourselves with ever more accuracy, do we risk changing what it means to be human? In a potential quest for the genetically ‘normal’, will we risk annihilating the very diversity and mutations on which evolution depends?

These are some of the questions that the Pulitzer prize-winning author, cancer geneticist and stem-cell biologist Siddhartha Mukherjee explored when he came to the Intelligence Squared stage in October 2016. Joining him was neuroscientist and BBC broadcaster Daniel Glaser, director of the Science Gallery at King’s College London and former Head of Engaging Science at the Wellcome Trust.

As we enter a new era of ‘previvors’ (people who have been screened for certain genetic predispositions) and post-humans (those who have altered their genetic propensities), will we use this technology responsibly? Can we, as Mukherjee asked, make our genomes a ‘little better’ without risking the possibility of making ourselves substantially worse?