In 2021, the psychologist and writer Kathryn Paige Harden co-authored a paper outlining her research into the genetic patterns linked to a higher risk of developing substance abuse problems or engaging in risk-taking behaviour, such as having unprotected sex or committing crime. The paper referred to the genetics of “traits related to self-regulation and addiction”, but Harden thought of herself as studying the genetics of sin.
Harden is a professor at the University of Texas and the author of a previous book, The Genetic Lottery, on how our knowledge of genetics should shape our views on meritocracy. She once received a letter from a man who has been in prison since he was 16 for kidnapping and sexually assaulting a woman. “What would drive a boy to do such a thing?” he asked her. Her new book is a heartfelt, subtly argued response to his question, an attempt to outline how our expanding knowledge of what makes people do bad things – the interplay of our inherited tendencies and our life circumstances – should influence how we assign moral responsibility and blame.
Harden was raised in a southern, evangelical “praise God and pass the ammunition” church, and although she left it, she writes that Christianity has lingered with her like childhood chicken pox: “You might recover but you are never free. The virus will live in your nerves until you die.” She retains a deep interest in theology, and while sin might seem to some readers an old-fashioned way of thinking about human behaviour she explores how Christian ideas about sin and forgiveness influence moral conversations today, and have helped shape the US’s extraordinarily punitive criminal justice system. Only in the US can a juvenile offender, such as the man who wrote to Harden, be imprisoned for life with no hope of parole – a policy that suggests an ongoing commitment to the doctrine of original sin, the notion that some people are born bad.
It has become almost compulsory for popular science writers to humanise their work by writing about themselves, but Harden is exceptionally skilled at interweaving the personal and the scientific. She writes about her own life experiences – leaving the church, becoming estranged from her parents, the challenges of early motherhood – with rare, dangerous honesty. These memoiristic sections also explore the challenge, and necessity, of building bridges between scientific theory – such as what studies of identical twins tell us about why some people find it harder to do the right thing – and our own, subjective experiences of what it means to be a moral agent.
The book is littered with fascinating scientific findings: who would have thought, for instance, that religiosity is largely genetically determined, so that step-siblings and adopted siblings who are raised in the same home are, by adulthood, no more similar in their religious outlook than two randomly chosen strangers, while twins raised apart often come to remarkably similar spiritual conclusions? Or that being in possession of certain minor physical anomalies, such as low ears or webbed toes, is correlated with being more aggressive? Or that paper wasps appear to punish greedy behaviour in the hive by attacking worker drones that aren’t pulling their weight and queens that eat too many eggs?
That paper wasps example points to the idea that moral feelings – such as gratitude, resentment or blame – are biologically encoded and enable social cooperation. The desire for retribution is an ancient impulse, and even young children enjoy watching a “bad” person get punished. But if science can demonstrate how little choice people truly have over their behaviour, should it render moral outrage obsolete? Some philosophers think so. Harden adopts a more nuanced position. To hold a personal morally responsible is to recognise them as fully human, she argues, but an awareness of the genetics and social components of sin ought to reshape our ideas about just punishment. A wrongdoer, on this model, ought to be humbled – but not debased, as so many are in America’s bloated and cruel prison system. Harden writes of Marcia Powell, a 48-year-old woman who died of heat exposure after being kept in an outdoor cage in an Arizona prison, having been arrested for propositioning a police officer. One hopes policymakers will read Harden’s book, but unfortunately the US carceral system has proved unresponsive to appeals to moral decency or logic.
Another thorny question Harden poses is: as we learn more about the genetics of sin, would it be wise to select embryos for higher self-control? Harden thinks not. First, societies benefit from moral differences – this is how moral progress and transformation happens – and from having rule breakers. For instance, many entrepreneurs were risk-taking, badly behaved teenagers who were able to put their maverick tendencies to good use because they grew up with multiple social advantages. Second, it is a eugenicist fantasy that “bad” biology can be identified and sequestered: people don’t conform to neat categories of good and evil. In this complex, thought-provoking book Harden explores the stories of some of the worst people you have heard of – death row murderers, child killers, terrorists – and asks her readers to contemplate an uncomfortable question: these people are not so very different from you and I. So how should a just society treat them?