Goodbye, nature vs nurture

Talking about nature and nurture as separate, clear-cut forces is far adrift from the complexities of developmental science, says Evelyn Fox Keller

An entanglement of genes and environment (Image: Julia Fullerton-Batten/Getty)An entanglement of genes and environment (Image: Julia Fullerton-Batten/Getty)

ONE of the most striking features of the nature/nurture debate, the argument over the relative roles of genes and environment in human nature, is the frequency with which we read it has been resolved (the answer is neither nature nor nurture, but both) while at the same time we see the debate refuses to die. So what is it that evokes such contradictory claims, that persists in confounding us? Indeed, what is the debate really about?

This turns out to be far from easy to explain because different kinds of questions take refuge under its umbrella. Some express concerns that can be addressed scientifically, others may be legitimate and meaningful but perhaps not answerable, and still others make no sense. One reason for the persistence of the nature/nurture debate, then, is that these questions are knitted together by ambiguity and uncertainty into an indissoluble tangle, making it all but impossible to stay focused on a single, well-defined, meaningful question.

Another important issue is that some of that ambiguity and uncertainty comes from the language of genetics itself. For example, we may read that the debate is about sorting contributions of nature from those of nurture, and trying to estimate the relative importance, but what exactly is meant by "nature" and "nurture"? Sometimes the distinction is between what is inborn and what is acquired after birth; more often, it is between genes and environment. But not only does nurture affect prenatal development, we also need to ask what exactly is a gene, and what does it do? What do we mean by environment? Does it refer to factors beyond the organism that affect its development, to the milieu in which the fertilised egg develops, or to everything other than the DNA sequence?

Finally, there’s the question of contributions. Contributions to what? This question is almost never posed, yet it is the most recalcitrant source of trouble with the nature/nurture debate. The reason is that the subject of debate depends critically on our tacit assumptions about how that question is to be completed.

A common assumption is that what is at issue is a comparison of the contributions of nature and nurture to the formation of individual traits. In his widely read book, Nature via Nurture, Matt Ridley argues that modern genomics has shown that, expressed that way, the nature/nurture debate invokes a meaningless opposition: "The discovery of how genes actually influence human behaviour, and how human behaviour influences genes, is about to recast the debate entirely. No longer is it nature versus nurture, but nature via nurture. Genes are designed to take their cues from nurture."

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