I had begun by trying, for the sake of scholarly thoroughness, merely to write a short chapter for my book on the ‘culturally disadvantaged’ that I expected would succinctly review the so-called nature-nurture issue only to easily dismiss it as being of little or no importance for the subsequent study of the causes of scholastic failure and success. I delved into practically all the available literature on the genetics of intelligence, beginning with the works of the most prominent investigator in this field, Sir Cyril Burt, whom I had previously heard give a brilliant lecture entitled The Inheritance of Mental Ability’ at University College, London in 1957. The more I read in this field, the less convinced I became of the prevailing belief in the all-importance of environment and learning as the mechanisms of individual and group differences in general ability and scholastic aptitude. I felt even somewhat resentful of my prior education, that I could have gone as far as I had—already a fairly well-recognized professor of educational psychology—and yet could have remained so unaware of the crucial importance of genetic factors for the study of individual differences.

Science is no stranger to controversy. The pursuit of discovery, of knowledge, is often uncomfortable and disconcerting. I have never been one to shy away from stating what I believe to be the truth, however difficult it might prove to be. This has, at times, got me in hot water. Rarely more so than right now, where I find myself at the centre of a storm of criticism. I can understand much of this reaction. For if I said what I was quoted as saying, then I can only admit that I am bewildered by it. To those who have drawn the inference from my words that Africa, as a continent, is somehow genetically inferior, I can only apologise unreservedly. That is not what I meant. More importantly from my point of view, there is no scientific basis for such a belief. I have always fiercely defended the position that we should base our view of the world on the state of our knowledge, on fact, and not on what we would like it to be. This is why genetics is so important. For it will lead us to answers to many of the big and difficult questions that have troubled people for hundreds, if not thousands, of years. But those answers may not be easy, for, as I know all too well, genetics can be cruel. My own son may be one of its victims. Warm and perceptive at the age of 37, Rufus cannot lead an independent life because of schizophrenia, lacking the ability to engage in day-to-day activities.

The conclusions of both behaviour genetics and evolutionary psychology remain distinctly unpalatable to many non-scientists, whose main objection is a superficially reasonable argument from incredulity. How can a gene, a stretch of DNA ‘letters’, cause a behaviour? What conceivable mechanism could link a recipe for a protein with an ability to learn the rule for making the past tense in English? I admit that this seems at first sight a mighty leap, requiring more faith than reason. But it need not be, because the genetics of behaviour is, at root, no different from the genetics of embryonic development…The idea of genes for behaviour is no more strange than the idea of genes for development. Both are mind-boggling, but nature has never found human incomprehension a reason for changing her methods.

Genetics is the study of similarity between relatives, and the problem of human genetics is that, in a species with a family and social structure and a taboo against manipulating individual life histories experimentally, there is a confounding between the similarity of relatives that arises from biological causes and the similarity that arise from social causes.

A better understanding of what science tells us about human genetic diversity is of immense importance, particualrly because it dispels false notions of what race is.

My youthful reasoning on the subject, however absurdly misinformed, nevertheless taught me a very valuable lesson: the danger of assuming that genes are responsible for differences we see among individuals or groups. We can err mightily unless we can be confident that environmental factors have not played the more decisive role.
This tendency to prefer explanations grounded in “nurture” over ones rooted in “nature” has served a useful social purpose in redressing generations of bigotry. Unfortunately, we have now cultivated too much of a good thing. The current epidemic of political correctness has delivered us to a moment when even the possibility of a genetic basis for difference is a hot potato: there is a fundamentally dishonest resistance to admitting the role our genes almost surely play in setting one individual apart from another.

The issue, rather, is this: Are we prepared to embrace the undeniably vast potential of genetics to improve the human condition, individually and collectively? Most immediate, would we want the guidance of genetic information to design learning best suited to our children’s individual needs?

It is no exaggeration to say that genes are essential to nearly every aspect of memory and the process of learning; without them, learning itself would not exist.

Anthropological geneticists should participate in because of the complexity of their work, its implications for human health and societies, and its tendency to be co-opted for particular political or social agendas. They are positioned to offer important contributions to public conversations on issues of race, genetic identity, history, and conflict. There are multiple avenues to public outreach for academics; among them, is a powerful, underused tool.

Since 1978, when a pail of water was dumped over my Harvard friend E. O. Wilson for saying that genes influence human behaviour, the assault against human behavioural genetics by wishful thinking has remained vigorous. But irrationality must soon recede. It will soon be possible to read individual genetic messages at costs which will not bankrupt our health systems. In so doing, I hope we see whether changes in DNA sequence, not environmental influences, result in behaviour differences. Finally, we should be able to establish the relative importance of nature as opposed to nurture.

Starting with the Minnesota twin study thirty-five years ago, and now with a mountain of data from twin, sibling, and adoption studies, we know that pretty much anything you can quantify about human personality, behavior, and intelligence is to some degree heritable, average-average at around the fifty percent level but sometimes much higher. We now in fact have a busy and exciting field of study called “behavioral genetics.” Given that all these traits are heritable, it follows from the ordinary laws of biology that different races will exhibit different statistical profiles on them. That’s not astonishing, mysterious, or horrible: It’s just first-floor-level science.

The future promises a detailed genetic dissection of personality, and it is hard to imagine that what we discover will not tip the scales of the nature/nurture debate more and more in the direction of nature—a frightening thought for some, but only if we persist in being held hostage by a static, ultimately meaningless dichotomy. To find that any trait, even one with formidable political implications, has a mainly genetic basis is not to find something set immutably in stone. It is merely to understand the nature upon which nurture is ever acting, and those things we, as a society and as individuals, need to do if we are better to assist the process. Let us not allow transient political considerations to set the scientific agenda. Yes, we may uncover truths that make us uneasy in the light of our present circumstances, but it is those circumstances, not nature’s truth, to which policy makers ought to address themselves.

Instead, in our world, nature's contribution to development comes not by providing a finely detailed sketch of a finished product, but by providing a complex system of self-regulating recipes. Those recipes provide for many different things-from the construction of enzymes and structural proteins to the construction of motors, transporters, receptors, and regulatory proteins-and thus there is no single, easily characterizable genetic contribution to the mind. In the ongoing, everyday functioning of the brain, genes supervise the construction of neurotransmitters, the metabolism of glucose, and the maintenance of synapses. In early development, they help to lay down a rough draft, guiding the specialization and migration of cells as well as the initial pattern of wiring. In synaptic strengthening, genes are a vital participant in a mechanism by which experience can alter the wiring of the brain (thereby influencing the way that an organism interprets and responds to the environment). There are at least as many different genetic contributions to the mind and brain as there are genes; each contributes by regulating a different process.

The finding that there is a substantial genetic component to our behavior should not surprise us; indeed, it would be far more surprising if this were not the case. We are products of evolution: among our ancestors, natural selection indubitably exerted a strong influence over all traits that have figured in our survival.