Nature, Nurture, and Nature-by-Nurture - Killing the Dichotomy

The primary purpose of this book is to provide a broad snapshot of recent findings showing how the environment and genes influence behaviour. At face value, this should be uncontroversial but unfortunately, the history of genetics includes eugenic movements and Lysenkoism. As a result, discussions of how nature and nurture affect behaviour have been dogged by polemic disputes because ideological views about their contributions have tended to cloud what is really an empirical question. This is in some ways exemplified by the book Not in Our Genes (Lewontin et al. 1984), which begins with a political confession from the authors – we are committed socialists – and starts with a chapter on right-wing politics and determinism. For us, the evidence, and not political or any other beliefs, is what counts and any ‘belief’ approach puts the desire for the world to be a certain way ahead of the evidence that it is not so, ultimately committing a version of the naturalistic fallacy – if something is ‘natural’, it is morally correct, which is clearly rubbish (also see Chapter 10). Infanticide, cannibalism, forced copulation (rape), and killing other members of your species (murder) are rife in nature, but it would be difficult to convince anyone of intelligence that these acts are moral because they are natural. Furthermore, ‘politically’ motivated arguments against ‘reductionism’, reducing complex behaviours to single causes, are frequently concocted to protect against a biological determinism that must be fought at all costs. However, as we hope to explain, acknowledging that there are genes underlying behaviour, even genes of large effect, is imperative if that is what the data tell us. After all, it is no use playing music to cows if milk yield is totally determined by genes and unaffected by the environment, and as we outline below, in a polygenic world that includes inevitable environmental effects and all manner of interactions, prediction is tricky and determinism dubious because of the probabilistic and complex nature of the gene–behaviour link. But again, even if single genes were completely responsible for single behaviours, which they cannot be in the strictest sense (see below), let us not fall into a naturalistic fallacy. Rather than engage in further fruitless arguments about world-views, this book explores exciting new findings about behaviour and where we go from here. Before moving on to these new advances and the interesting questions that arise from them, we wish to make another – a final? – attempt to kill the nature versus nurture polarity