Why scientists must fight off the DNA determinists

Genetic determinism has never been less justified but it is pushing its way back onto the agenda
December 12, 2018

article body image

One idea to have pushed its way back on to the scientific agenda is genetic determinism, the belief that genes determine the greater portion of human behaviour—that what we are and all we can achieve is encoded like a blueprint in our DNA. In psychologist Robert Plomin’s recent book Blueprint: How DNA Makes Us Who We Are, for example, it is possible to see a version of this “hereditarianism,” albeit it in a more caveated and less crude form than is traditional. It is a dangerous strain of thought.

The paradox is that genetics research in the last couple of decades has only affirmed that complex psychological traits, including intelligence, involve thousands of genes and crucially also large environmental components. There has never been less justification for biological determinism.

Indeed, for those at the bottom of the class heap, differences in performance in intelligence tests have been shown to have zeroheritability. In other words, genes may account for next to nothing if a child is raised in an environment that doesn’t meet her basic needs. Thinking otherwise is a pathology with a dark history.

But then it has always been useful for the winners in any society to find an exogenous basis for their success—think, for example, of the divine right of kings; of the racial ideology that underpinned the slave trade; or, of the fatalist thinking in the Victorian hymn “All Things Bright and Beautiful”: “The rich man in his castle / The poor man at his gate / God made them high and lowly / And ordered their estate.”

The notion of heritability as destiny fulfilled the same role, and so was latched on to in the early 20th century, propelling the eugenics movement. Scientists and politicians were mesmerised by the belief that society has little effect on who we are, and that left to our own devices, the fittest will survive—what’s more, that this is how it should be. Donald Trump and some of his supporters have occasionally been described as social Darwinists in this vein.

More than ever, scientists need to learn from the past. It has always been in the interests of some to push the political ideology that we should be left to fend for ourselves, that investment in welfare is good money after bad. Scientists must be on very sure ground before they give such self-serving determinists more fodder. They should concentrate instead on engaging with historians and social scientists to better understand humans not as simple biological machines but as complex, social beings.

Read more new thinking for 2019