Many people were first introduced to the core issues of this book through the 1978 film The Boys from Brazil, based on a popular Ira Levin novel. In that story, the infamous Nazi doctor Josef Mengele tried, using genetic techniques and controlled childhood environments, to breed ninety-four clones of Adolf Hitler (the “boys” of the title). The hope was that these young men who had the Führer’s genes and were reared in conditions similar to the young Adolf’s would mature into creators of a Fourth Reich. Most critics found the film farfetched, but cloning is now a reality for certain animals, and the fears raised by the novel and film have returned. In the concluding chapter of Living with Our Genes, Dean Hamer and Peter Copeland tell a mini-tale of a clone they call Andrew who, as an adult, campaigns to stop those scientists who see no difference between cloning sheep and mass-producing humans. These cautionary tales center on the question of how much human behavior is determined by genes and how much this behavior can be manipulated by modifying the environment.
The scientist and journalist who wrote Living with Our Genes stress the evidence for the genetic control of human behavior. Hamer, who received his doctorate in biological chemistry from Harvard University, heads the Section on Gene Structure and Regulation at the National Cancer Institute in Bethesda, Maryland. He gained wide attention (and notoriety) through his discovery of the heritability of male homosexuality. In fact, the authors of Living with Our Genes previously wrote The Science of Desire: The Search for the Gay Gene and the Biology of Behavior (1994), which dealt with how Hamer discovered the genetic basis of male homosexuality and how he dealt with the controversy this discovery provoked. The Science of Desire was a successful book (The New York Times named it one of the “Notable Books” of 1994), and in Living with Our Genes, Hamer and Copeland have continued their collaboration. Hamer handled the explanations of scientific research, and Copeland used his journalistic skills to make Hamer’s ideas understandable to nonscientists.
According to Hamer and Copeland, nonscientists need to know why humans behave the way they do. In the past, religious explanations were satisfactory, but in the twentieth century, scientists have attempted to explain human behavior in terms of genetics (nature) and the environment (nurture). Geneticists use the term “nature” to refer to what people generally think of as biological inheritance and what scientists see as the differences in the deoxyribonucleic acid (DNA) molecule transmitted from generation to generation. For many scientists, a person’s inherited biological nature is not sufficient to explain his or her behavior; these scientists emphasize that humans behave the way they do because of their social conditioning (nurture). Hamer, a molecular geneticist, tends to emphasize that human behavior is heavily influenced by genes, which he sees as “the single most important factor” determining an individual’s uniqueness. This does not mean that genes make people into molecular robots, since human genes program them to respond creatively to complex and changing environments.
The theme of Living with Our Genes is that genes control many core personality traits such as how we eat, drink, feel, think, and interact with others. Each chapter begins with a specific human situation, for example the meeting of two people with strongly contrasting personalities at a class reunion. The authors then discuss the scientific research that has been done to illuminate the behavioral issues that they have raised, for example a twin study that shows that a trait such as shyness is influenced by genes. Sometimes the authors play the role of reductionists, insisting that a woman has as much choice in her personality as she does in the size of her feet, but they also point out that the genes controlling personality are very flexible, allowing humans to adapt in various ways to life’s complexities.
Hamer and Copeland use the distinction between temperament and character to bolster their position as moderates in the nature- nurture controversy. Unlike other psychologists, they use temperament to refer both to how people feel about the world and to how they act. Indeed, temperament is the focus of their book: “what it is, how to recognize it, and where it comes from.” They attack those social scientists who deny that inborn temperament exists and who believe instead that human beings are solely products of their environment. On the other hand, they avoid the excesses of those reductionists who claim that humans are nothing but molecular machines by qualifying their enthusiasm about genetic explanations. Genes do not program people to behave only in certain ways. Human beings are born with particular temperaments, but these are not created fully formed—they evolve in response to the environment. The authors are ideological liberals; they want to see the knowledge they convey used by their readers as a tool for liberation.
The genetics of behavior can help humans in their quest for liberation. For example, scientists have discovered a temperamental difference called novelty seeking. Novelty seekers find pleasure in intense and unfamiliar experiences, and a study of identical and fraternal twins revealed that this behavioral trait had genetic roots. Some scientists wondered whether dopamine, the “pleasure chemical,” is related to novelty seeking. One study found that the gene making a particular dopamine receptor called D4DR was very important, and in his laboratory, Hamer confirmed that the D4DR gene was affecting novelty-seeking behavior.
Despite their emphasis on genes predisposing people to particular behaviors, the authors also stress that human character can control genetic predispositions. For example, the human brain is genetically programmed to be capable...