Review of Copeland & Hamer (1998) "Living with Our Genes"
CBC “Quirks & Quarks” 28 May 1998

    “Is it genetic?” It’s well-known that, if you’re yellow & round (and a pea) and marry someone green & wrinkled, your baby peas will all be yellow & round. Your grand peas will be more varied, but some will be as like you as, well, two peas in a pod. That's Genetics: the science of sorting out the rules that govern such family resemblances. Do such rules extend to humans? We know they do. But do they explain such complex behavioural and personality traits as intelligence and sexual orientation?

    That’s the question asked by Dean Hamer, a geneticist at the US National Cancer Institute, and co-author Peter Copeland, in “Living with Our Genes,” a popular account of recent research on the genetics of behavior and personality. Their answer is, simply, Yes: “People are different because they have different genes that created different brains that formed different personalities.” Their case is presented in eight chapters called “Thrills,” “Worry,” “Anger,” “Addiction,” “Sex,” “Thinking,” “Hunger,” and “Aging.”

    Hamer & Copeland try to make the case for direct connections between particular stretches of DNA and specific human personality traits. We are told, “Everyone has a ‘mood gene,’ and a ‘sexual orientation gene,’ and a gene that regulates body weight.” I have to say that I found their argument unconvincing. The scientific evidence is oversimplified, and we’re typically told, rather than shown, what’s so. The presentation is glib, often to the point of absurdity, and is sometimes downright crude.

    Nuryevean leaps abound.  The pervasive influence of genes is illustrated by a pair of identical twins, separated at birth, who on reunion discover they are both twice married, first to Lindas then to Bettys, have sons named Alan, pets named Toy, and identical tastes in smokes and sodas. Studies of twins are an important method of genetic research, but this kind of argument is just silly.

.    Flat statements oversimplify complex issues. In “Thinking,” we’re told, “The evidence that IQ is largely inherited is overwhelming.” Nonsense. There is ample evidence that IQ test scores show high heritability. Whether there is any single trait called “intelligence” for such tests to measure is highly debatable. Heritability studies do not identify specific genes in individuals, they measure the degree of genetic influence on traits in populations. The interplay of genes and environment is complex, and a trait that is highly heritable in one environment may not be at all heritable in another. Heritable traits can vary enormously between parent and offspring. Heritability is not inevitability.

    The presentation is by turns reasonable and racy. We read, “Yes, we are born with a certain genetic makeup. No, that doesn’t mean we have no control over our lives . . .  It’s not nature or nurture, it’s nature and nurture.” Quite true. But then we’re told: “[A] person might have the genetic makeup typical of a mass murderer; but he could turn out to be the next great professional linebacker.

    Genes undoubtedly influence behavior and personality, but such crude generalizations misinform the reader and are dangerous if used as a basis for social policy. Early on, Hamer & Copeland dismiss the theory of environmental determinism, the idea that ”environmental influences [are] the only thing necessary to understand a human being.” This, they say, is “not only stupid but cruel.” The same can be said of theories of genetic determinism, and of this book.

    For Quirks and Quarks, I’m Steve Carr in St. John’s.

All text material ©1998, 2010 by Steven M. Carr