Wrestling with Behavioral Genetics: Science, Ethics, and Public Conversation
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《新英格兰医药杂志》
Behavioral genetics has now entered the molecular era, as indicated by the publication of high-profile reports on the influence of genes on neurotransmitter function and metabolism as well as on brain growth factors. Variations within populations in imaged brain function, and in the risks of major depression, obsessive–compulsive disorder, and bipolar affective disorder, have all been reported. A series of replicated reports on genetic variants in schizophrenia and alcohol dependence has given a new stimulus to work being done on neurobiologic mechanisms of disease.
The identification of specific genes influencing human behavior has profound implications. We would agree now, I think, that there is no "gay gene" but that many genes influence human sexuality, and that there is no "murderer gene" but there are genes that influence impulsivity and aggression. Genes do not cause behavior, but they affect tendencies to behave in certain ways.
These are the issues addressed by Parens, Chapman, and Press in Wrestling with Behavioral Genetics. They have solicited contributions from 14 authors who are experts in neurobiology, sociology, philosophy, law, and journalism. The book springs from a program supported by the National Human Genome Research Institute. The results of the editors' efforts, however, are not perfect. The chapters vary in tone and are uneven in quality. The best chapters, in my view, are those that spring from sociology and law.
The editors' introduction sets the stage with an essential historical introduction to eugenics, the misinterpretation of data on the XYY genotype, and the controversies centered on differences in IQ scores according to race and ethnic group. Kenneth F. Schaffner contributes two chapters that are notable for their imaginative dialogue between a behavioral geneticist and a fictional jurist, Judge Jean. These chapters provide a good introduction for nonspecialists to the principles of quantitative genetics. However, an understanding of new discoveries in molecular genetics as they are related to behavior requires expertise in behavioral and "psychiatric" genetics that is not represented here.
The first section of this book examines basic scientific concepts and debates. The second section begins with a contribution by Press on the medicalization of behavioral conditions. Is obesity an illness? The answer depends on multiple variables, only one of which is the existence of genetic variants related to weight. In a chapter on the link between crime and race, Troy Duster rightly admonishes us to avoid genetic explanations in discussions of race or ethnic group and of complex variables such as rate of incarceration. However, he does not provide guidance for approaching differences that are undoubtedly genetically influenced, such as variations in alcohol metabolism in East Asian populations or the prevalence of sickle cell disease among black persons. Interesting questions are posed in a chapter by Harold Edgar regarding impulsivity, genetics, and criminal law. It seems unlikely that "tendencies" that are related to genetic associations with complex temperamental traits would ever be regarded as exculpatory in American criminal courts.
The chapters on equality, normality, and moral responsibility are philosophical in tone. They make for interesting reading, but they seem to pose a straw-man argument: "If DNA determines our , then the following ethical and social problems arise: ." DNA is no more deterministic (with rare mendelian exceptions) in its influence on human growth, development, and behavior than is diet or upbringing. DNA influences behavior through RNA and protein, which are eminently adaptable, since gene expression changes in response to environment.
The third section is the best portion of this book. Promoting public conversation about behavioral genetics will be increasingly pertinent to creating enlightened, fair, and representative public policy. The chapter by Leonard Fleck provides several examples of the dilemmas for public policy related to genetic testing for complex traits, taking an appropriately probabilistic approach to the outcomes discussed. Fleck describes a process for approaching a question of substantial public interest in which community values would permit more than one decision. His first criterion for an effective deliberative process can be stated as a question: Do participants find themselves internally conflicted regarding the decision? If the answer is yes, then there is hope for a process that will be constructive — a process that often requires a Socratic dialogue.
In their chapter, Celeste Condit et al. find that most laypeople already believe that genes play a role in human behavior. The idea is not foreign; it is, however, sometimes expressed in ways that are not consistent with modern concepts of gene function. The history of media reports in this area is full of missteps — scientific or journalistic or both. Rick Weiss, in his chapter, emphasizes that press coverage of genetic findings is becoming increasingly sophisticated, and he appends recommendations for caution and for the recognition of complexity. As he says, the gathering of appropriate knowledge in this area is a big assignment for a writer, but it is "not too much to ask as we chase what is, really, the only story ever worth writing: the story of who we are as humans, and what makes us tick."
That sentence is not bad for a coda, and this is not a bad book. Consider it a first pass that should be a stimulus to a more enlightened discussion. The "wrestling" will go on for some time to come.
John I. Nurnberger, M.D., Ph.D.
Institute of Psychiatric Research, Indiana University
School of Medicine
Indianapolis, IN 46202(Edited by Erik Parens, Au)
The identification of specific genes influencing human behavior has profound implications. We would agree now, I think, that there is no "gay gene" but that many genes influence human sexuality, and that there is no "murderer gene" but there are genes that influence impulsivity and aggression. Genes do not cause behavior, but they affect tendencies to behave in certain ways.
These are the issues addressed by Parens, Chapman, and Press in Wrestling with Behavioral Genetics. They have solicited contributions from 14 authors who are experts in neurobiology, sociology, philosophy, law, and journalism. The book springs from a program supported by the National Human Genome Research Institute. The results of the editors' efforts, however, are not perfect. The chapters vary in tone and are uneven in quality. The best chapters, in my view, are those that spring from sociology and law.
The editors' introduction sets the stage with an essential historical introduction to eugenics, the misinterpretation of data on the XYY genotype, and the controversies centered on differences in IQ scores according to race and ethnic group. Kenneth F. Schaffner contributes two chapters that are notable for their imaginative dialogue between a behavioral geneticist and a fictional jurist, Judge Jean. These chapters provide a good introduction for nonspecialists to the principles of quantitative genetics. However, an understanding of new discoveries in molecular genetics as they are related to behavior requires expertise in behavioral and "psychiatric" genetics that is not represented here.
The first section of this book examines basic scientific concepts and debates. The second section begins with a contribution by Press on the medicalization of behavioral conditions. Is obesity an illness? The answer depends on multiple variables, only one of which is the existence of genetic variants related to weight. In a chapter on the link between crime and race, Troy Duster rightly admonishes us to avoid genetic explanations in discussions of race or ethnic group and of complex variables such as rate of incarceration. However, he does not provide guidance for approaching differences that are undoubtedly genetically influenced, such as variations in alcohol metabolism in East Asian populations or the prevalence of sickle cell disease among black persons. Interesting questions are posed in a chapter by Harold Edgar regarding impulsivity, genetics, and criminal law. It seems unlikely that "tendencies" that are related to genetic associations with complex temperamental traits would ever be regarded as exculpatory in American criminal courts.
The chapters on equality, normality, and moral responsibility are philosophical in tone. They make for interesting reading, but they seem to pose a straw-man argument: "If DNA determines our , then the following ethical and social problems arise: ." DNA is no more deterministic (with rare mendelian exceptions) in its influence on human growth, development, and behavior than is diet or upbringing. DNA influences behavior through RNA and protein, which are eminently adaptable, since gene expression changes in response to environment.
The third section is the best portion of this book. Promoting public conversation about behavioral genetics will be increasingly pertinent to creating enlightened, fair, and representative public policy. The chapter by Leonard Fleck provides several examples of the dilemmas for public policy related to genetic testing for complex traits, taking an appropriately probabilistic approach to the outcomes discussed. Fleck describes a process for approaching a question of substantial public interest in which community values would permit more than one decision. His first criterion for an effective deliberative process can be stated as a question: Do participants find themselves internally conflicted regarding the decision? If the answer is yes, then there is hope for a process that will be constructive — a process that often requires a Socratic dialogue.
In their chapter, Celeste Condit et al. find that most laypeople already believe that genes play a role in human behavior. The idea is not foreign; it is, however, sometimes expressed in ways that are not consistent with modern concepts of gene function. The history of media reports in this area is full of missteps — scientific or journalistic or both. Rick Weiss, in his chapter, emphasizes that press coverage of genetic findings is becoming increasingly sophisticated, and he appends recommendations for caution and for the recognition of complexity. As he says, the gathering of appropriate knowledge in this area is a big assignment for a writer, but it is "not too much to ask as we chase what is, really, the only story ever worth writing: the story of who we are as humans, and what makes us tick."
That sentence is not bad for a coda, and this is not a bad book. Consider it a first pass that should be a stimulus to a more enlightened discussion. The "wrestling" will go on for some time to come.
John I. Nurnberger, M.D., Ph.D.
Institute of Psychiatric Research, Indiana University
School of Medicine
Indianapolis, IN 46202(Edited by Erik Parens, Au)