In 2010, researchers launched a study, the Strong African American Families project, in one of the bleakest, most impoverished areas of rural Georgia, a place overrun by alcoholism, violence, mental illness and drug use. “Abandoned clapboard houses with broken windows dot the landscape,” Siddhartha Mukherjee tells us. “Crime abounds. Vacant parking lots are strewn with hypodermic needles. Half the adults lack a high school education and nearly half the families have single mothers.” You get the picture.
The scientists wanted to know how an individual’s genetic makeup might help or hinder their chances of surviving this grim background, and so began testing local families to determine which variant of a gene known as 5-HTTLRP they possessed. One, known as the short variant, had previously been linked to individuals prone to depression, alcoholism and anxiety. The other, the long variant, was associated with relative “normality”.
Sure enough, the scientists found that possessors of short variants were more likely to binge drink, use drugs and be sexually permissive. Combine a deprived background with a set of “bad” genes and your chance in life was doomed, it appeared. But the researchers went further, providing counselling for short-variant binge drinkers and long-variant “normals” to see how each group responded to help from others. They found the former group, while more prone to antisocial behaviour, was also more likely to react positively to counselling. That grim start to life was not quite so hopeless as it seemed. “It is as if resilience itself has a genetic core,” says Mukherjee in this broad-ranging guide to modern genetics and its impact on life.
The idea of a resilience gene has since taken root, leading psychologists to propose that susceptible short-variant children – the worst behaved but better at responding to counselling – be targeted for scarce and costly intervention. To his credit, Mukherjee is suspicious of the ethics of a scheme whereby an authority, having genotyped children in a particular area, could then be allowed to choose who is worthy of the attention of the best teachers and the most resources and who is not. Put that way, the notion looks unpleasant.
The trouble, says Mukherjee, is that we are going to encounter this sort of thing increasingly often as our ability to unravel the DNA of our fellow citizens becomes more powerful. And that refers not just to interventions we might make in a person’s upbringing but to those whose DNA we may be able to change. Already scientists are finding ways to alter the genetic makeup of children with harmful mutations including cystic fibrosis and muscular dystrophy. Soon, we will start to tackle more complex disorders – cancers or heart diseases – by altering or replacing entire groups of genes. “We have reached the stage where, as intelligent organisms, we are learning how to read the instructions for our own creation,” says Mukherjee. “Soon we will be ready to write our own instructions. In other words, we will be able to manipulate our own genetic future, snipping genes from embryos or adding new ones.”
The question is: who will choose what procedures are acceptable and who receives them? And what might be the unintended consequences? Illness might progressively vanish, but so might identity, if we tinker too much, says Mukherjee. Similarly, grief might be diminished but so might tenderness.
These are intriguing questions and, in trying to find answers, Mukherjee takes us on a journey that begins with the tribulations of his own family. He has two uncles and a cousin affected by schizophrenia and bipolar disorder; the question of whether he and his relatives are affected by a genetic predisposition to the conditions clearly concerns him. “Madness, it turns out, has been among the Mukherjees for at least two generations,” we are told. This is Mukherjee’s intimate history and it is touchingly related – though in truth it only forms an intermittent part of his narrative. The major part of The Gene is made up of a sweeping history of genetics that takes us from its dawn – with the garden pea experiments of Gregor Mendel, who revealed the existence of individual units of heritability – to modern gene-editing techniques, which allow scientists to alter or replace genes more or less at their leisure. It is an ambitious trip, to say the least.
Such efforts are welcome. This is a big book, bursting with complex ideas; without careful presentation, the reader would have struggled. Yet it is not without critics. An extract published last month in the New Yorker attracted strong censure from several biologists for misrepresenting the way our environments can affect the actions of genes, drawing a robust response from Mukherjee.
I have different qualms. For a start, I found the book’s priorities erratic. The key story of how DNA analysis showed Homo sapiens once interbred with our evolutionary cousins, the Neanderthals – the work of Swedish researcher Svante Pääbo – is dismissed in a few paragraphs while page after page is devoted to the work of US geneticist Dean Hamer, who in 1992 claimed to have found a “gay gene” that explained homosexuality in men – even though no gay gene has since been found, Mukherjee eventually admits. So why devote umpteen pages to the subject?
The latter stages of the narrative also present us with a rather irritating American triumphalism, as we progress through the late 20th and early 21st century to our modern mastery of the gene. Mukherjee tells us that, in 1980, David Botstein and his Massachusetts Institute of Technology colleagues were responsible for publishing the first proposal to use DNA variations to create a map of the human genome, a notion crucial to the subsequent launching of the Human Genome Project. In fact, Britain’s Walter Bodmer and Ellen Solomon had already outlined the idea in 1979, in the Lancet. The omission is slipshod.
Fortunately, these flaws do not detract seriously from an otherwise well-written, accessible and entertaining account of one of the most important of all scientific revolutions, one that is destined to have a fundamental impact on the lives of generations to come. The Gene is an important guide to that future.