Under the Spell of Genes

Behavioral Genetics, The Clash of Culture and Biology By Carson Ronald A., Rothstein Mark A. Baltimore MD: Johns Hopkins University Press (1999). 206 pp. $39.95Several years ago, one of our graduate students presented a journal-club paper that proposed monoamine oxidase A as a candidate gene for what appeared to be an inherited, male-specific aggressive behavior in one family. With a skepticism that lies somewhere between a healthy scientific circumspection and the hubris of youth, the student pooh-poohed the notion, but at the heart of it, I sensed the embrace of political correctness at the expense of unbiased truth. Soon of course, mutations in the gene were discovered, pharmacological therapies were developed, and a knockout mouse was found to exhibit aggressive behavior, firmly establishing a deficiency of monoamine oxidase A as a basis for aggressive behavior.Even the monoamine oxidase A story, though, is the exception. For many behavior traits, such as schizophrenia, alcoholism, “thrill-seeking” behavior, or homosexuality, the genetic underpinnings are much murkier. As the public is tossed and turned by preliminary announcements of genes for this or that, we are often both fascinated and appalled that our behavior may be reduced to a few bases of DNA.As a molecular biologist, I admit that I tend to favor the genetic reductionist view. Thus, I approached Behavioral Genetics, The Clash of Culture and Biology with some trepidation, wary that the elusive nature of behavioral genes would provide an argument against their existence altogether.I need not have worried. Behavioral Genetics is a balanced and informative collection of essay that attempt to define the scientific issues facing the field and the possible repercussions for our society that stem from these studies and their conclusions.Following an introduction and cautionary tale by Allan Tobin on genetic reductionism, two chapters are devoted to the nuts and bolts of how behavioral genetics is practiced in the field. The chapter by Rowe and Jacobson reviews the field, founded by Sir Francis Galton. The authors point out how the pendulum has swung from the view of genetic determinism espoused by Galton and the eugenics movement at the early part of this century, to the acceptance of environmental effects on behavioral in the 1950s and 60s, and now back again. The chapter ends, though, with a soporific flowchart depicting the scientific process by which one teases out genetic and environmental influences on behavioral traits. Stephanie Sherman and Irwin Waldman then pick up the torch and succinctly describe the statistical approaches used to find genes involved in behavioral traits.For me, the strongest feature of the book was the two chapters (by Mark Rothstein and Lori Andrews) that dealt directly with the legal implications of behavioral genetics. Indeed as much of this topic was new to me, I could easily have read an entire book on the subject. Behavior genetics in the context of the criminal justice system is a particularly compelling issue. If we embrace genetic determinism, or for that matter, cultural determinism, where is the room for free will? Culpability in criminal law requires a voluntary wrongful act and the mental state to realize that the act is wrongful. If a genetic defense is used, other issues are raised as well. Who will pay for the genetic testing if the defense grasps at genetic straws? If a jury decides that a defendant is innocent on the grounds of genetic predisposition, what are the implications for others with similar genetic predisposition? Will they be stigmatized or feared or even kept under surveillance?While many of the authors are correct to point out epigenetic and environmental influences on behavior, only one took great pains to argue against genetic reductionism. In his chapter, Kenneth Schaffner asks whether any behavioral trait can have a purely genetic explanation and goes on to answer “no.” His argument—that genes encode proteins which interact with other proteins, and that neurons, not genes, control behavior—struck me as clumsy and semantic.Multiauthor compilations such as this one inevitably suffer from a number of problems. The writing is spotty, and there is considerable overlap between some essay. At least two authors describe the circuitous history of behavioral studies on schizophrenia, for example. However, the most dissatisfying aspect of the book is that the most recent literature citations are from 1997, while the publication date is 1999. Since the reader is now primed to care about the genetics of schizophrenia, she wants to know “how did it all turn out in the end?”Despite these flaws there is a place on every human geneticists bookshelf for Behavioral Genetics. Not only are parts of it well worth reading, it is chock full of illustrative annotations and references.