Living With Our Genes: Why They Matter More Than You Think. - Review - book reviews

Journal of Sex Research,  Nov, 1998  by Ray H. Bixler

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Living With Our Genes: Why They Matter More Than You Think. By Dean Hamer and Peter Copeland. New York: Doubleday, 1998, 355 pages. Cloth, $22.95.

Reviewed by Ray H. Bixler, Ph.D., University of Louisville, Department of Psychology, Louisville, KY 40292.

Pop art on the dust jacket provoked alarm--"Why did I agree to review a book like this!" The first few pages, including a quote from Popeye, intensified my discomfort. Having now read the whole work, I feel obliged to warn others not to judge this book by its cover.

Each chapter begins with the problems of one or more fictional characters used as jumping off points for lively discussions of topics such as worry, anger, and sex. This popular style, which should appeal to college students and other young adults, effectively conveys the subtle and complex interaction of heredity and environment.

Hamer and Copeland have produced a thorough survey of research and an excellent analysis of nature and nurture in determining behavior. Initially they play down the functions of rearing, education, and subculture. "We come in large part ready-made from the factory" (p. 11). Nevertheless, "genes are not fixed instructions ... (although) they do determine the range of what is possible" (p. 12).

In their introduction to "Behavior Genetics" the authors emphasize that parents should be aware that unique hereditary predispositions play a prominent role in the development of their children. Each child should be assisted to develop his/her own unique potential. It follows that we must avoid trying to mold them to meet our expectations rather than their own.

Studies of the behavior patterns of identical and fraternal twins illustrate the importance of heredity in determining behavior. Identical twins, whether reared together or in different families, are much more likely to exhibit similarities in behavior than are fraternal twins reared together.

We are introduced to the O'Rourke brothers, Charles and Michael, who exhibit striking differences in novelty-seeking behavior in spite of being reared in the same environment by the same parents. Hamer and Copeland then trace the research that led to the discovery of the specific genetic determinants of novelty-seeking. We are warned, however, not to forget that differing environmental influences almost certainly had an effect on the brothers. Like all the illustrations this is presented in an engrossing manner, comprehensible to lay as well as professional readers.

The chapter on "Worry" surveys the history of attempts to adapt by those whose behavior is dominated by persistent shyness and unjustified fears of being harmed. The importance of genetic factors is buttressed by animal studies in which the amygdala has been demonstrated as crucial in the experience of fear.

Hamer and Copeland cite the suicides of Ernest Hemingway and his siblings as suggestive of the role of heredity in depression, but quickly--and properly--note the fact that just because a trait "runs in the family doesn't necessarily make it genetic" (p. 66). Studies of identical and fraternal twins sharply reduce this confusion. References to research by several investigators (including Adam Matheny and David Wechsler, both of whose names are misspelled in the text and index) document the role of heredity in human boldness and shyness.

An explanation of the function of the brain chemical serotonin in the reduction of tension is illustrated by Sally, whose severe depression did run in the family (and here the authors clearly assume this to be genetically significant). She was effectively treated with Prozac. Serotonin's role in reducing violent behavior is impressively documented with summaries of research with both animals and humans.

"Anger" is introduced by involving the reader in a series of events, which begin with "Just as you are clearing your desk to pick up your son at the day-care center ..." (p. 87). One frustrating, demeaning act after another lead to the amygdala taking over the role normally played by the cerebral cortex. Hamer and Copeland believe that in these circumstances the worst one can do is to follow the advice of psychotherapists who urge us to vent our anger. Instead, they recommend turning the other cheek. There is substantial evidence, however, contradicting this advice. For example, children often adapt much better to their young siblings after having pummeled a baby doll in play therapy (Bixler, 1949).

The authors contend that the combination of heredity and environment, not either alone, determines whether one will become violent. This is technically correct, of course, but also misleading. Heredity and environment have a multiplicative, rather than additive relationship. If either is abysmally bad, it overwhelms the influence of the other. A bit later we are told that environment has little effect if one's heredity is "good"; however, environment is crucial if pathological heredity is involved. In this chapter Hamer and Copeland give very brief, but effective, coverage of fear, contending it prevents our behaving in ways which endanger our survival.