Born That Way Page 2

  All of these reactions, concerns, judgments, and decisions might seem products of conscious thoughts. Or, with more reflection, some might be traced to the woman’s experience, upbringing, or social conditioning. They may, in fact, have sprung from none of these, but may have been prompted, wholly or in part, by her genes, those infinitesimal bits of DNA, which thirty years of research tells us influences our personalities, our behavior, and how we respond to the world around us. As the woman goes about her day, she draws on her reasoning power to deal with special situations. Much of the time, however, she is, like most of us, on semiautomatic pilot, reacting to whatever the environment throws at her with ebbs and surges, blips and flashes, of chemical, gene-rooted responses. As with all humans, her behavior is shaped and guided by signals from the biochemical motherboards that genes have created in each of us.

  The interaction between genes and environment is, we now know, essential to the developing child—and for psychologists the term “environment” means every influence on an organism that is not genetic. Not only in children, but in adults too, the environment can have powerful effects. But to a greater degree than ever before realized, the genetic influences on behavior, barring an extraordinary childhood (malnutrition, social deprivation, prolonged abuse), express themselves pretty much as configured before birth.

  Scholars have traditionally divvied up the human into an array of discrete vantage points—anatomy, psychology, anthropology, sociology, economics, political science, history. We now see these disciplines converging on a component of our physical selves that mounting evidence indicates is the underlying basis of it all: the twenty-three pairs of chromosomes, containing approximately 100,000 genes, that exist in every human cell. Whatever the term—chromosomes, genes, DNA, the double helix, nucleic acids, ribosomes, alleles—all refer to our biochemical blueprints.

  Genetic discoveries have been receiving so much press that non-scientists can be forgiven for seeing the DNA furor as a fad, a New Thing steamroller, this year’s channeling or biorhythms. The world appears so in the grip of a double-helix dither that less excitable types shrug it off as a hyped-up media ploy to make the news of the day appear different from the news of last week. Unfortunately for people already bored with gene palaver, the ramifications of this scientific earthquake will continue unfolding, and making news, well into the next century. And the possibilities this knowledge opens up are vast.

  Many of the most riveting findings have been of a high-priority medical nature, the genetic roots of birth defects and diseases that, throughout time, have plagued humanity. Because of the widespread suffering caused by these genetic mishaps—British geneticist Steve Jones states that one child in thirty is born with a genetic irregularity of one sort or other—the excitement over genetic therapies is understandable. More recently, the sensational news about cloning a sheep from a mature cell has seized the spotlight from even the landmark medical breakthroughs.

  Important as these advances are, they have overshadowed a concurrent, and in some ways more momentous, revolution—the burgeoning understanding of genetic links to personality and behavior. A mass of research that has been building over the past two decades has forced most psychologists and other social scientists to acknowledge what they had long denied: Genes influence not just physical characteristics such as hair color and susceptibility to cancer but our personalities, temperaments, behavioral patterns—even personal idiosyncrasies, the quirks and foibles that make each person unique.

  Since behavior is the subject of this book, and the term is broad enough to glaze the eyes of nonprofessionals, it might be a good idea to consider what the word means to scientists. For them, behavior is everything the organism does and thinks—from crying for its mother to delivering a Nobel acceptance speech. Ambition is behavior; so are laziness, rebellion, and compassion. Patriotism, sexism, hating your boss, and loving the Lakers—all are forms of behavior. Virtually anything the individual does, any product of the brain, any action, any mood, emotion, mannerism, or tic, is lumped under the umbrella word “behavior.”

  From the beginning of the brief hundred years that the mechanics of inheritance have been unfolding, science understood that genes were the building plans for our bodies and brains, the human machine that seemed to be able to think and behave in unlimited numbers of ways. Patterns and constraints were imposed on behavior from the external world, especially from the culture and its primary agents, parents. Now we see that this picture is not accurate. Many patterns and constraints are imposed by culture, but many others, the new evidence shows—along with batteries of impulses, leanings, attitudes, susceptibilities, aptitudes—are born with us.

  It is hard enough for nonscientists to conceive of a few microscopic specks of nucleic acid containing the instructions for growing an arm, an ear, or a kidney. Now research says we must grasp as well that similar specks can also go far toward determining if we are to be happy or morose, passive or aggressive, bright or dim, liberal or conservative, religious or atheistic. “Phenotype” is the word scientists use for each genetic manifestation. (Genotype refers to an organism’s entire complement of genes, the overall blueprint for each species.) A leg is a phenotype; so are arms, ears, and kidneys. Geneticists have come to consider behavior (or behavioral propensities) just another phenotype.

  Among those pursuing this research, some focus on specieswide traits, seeking out the evolved behavioral template shared by everyone. These are the evolutionary psychologists and sociobiologists who try to identify the broad traits that have evolved to make up human nature—aggression, competitiveness, sociality, and altruism would be a few. Behavioral geneticists, on the other hand, are more interested in individual differences. They are ferreting out the genetic influences, if any, that make one person fearful, another bold, one optimistic, one pessimistic, one placid, one fretful. They are also seeking the specific genetic configurations that abundant evidence indicates interact with the environment to produce such common behavioral problems as depression, addiction, obesity, and autism.

  An unexpected product of this research is the ever-narrower behavioral nooks and crannies that reveal a genetic component. For most of us it is not difficult to accept at least partial genetic orchestration of broad categories of temperament such as shyness, pessimism, and boldness, among others. Narrower traits, however, such as compassion, extravagance, rule-flouting, and risk-taking, can, without too great an effort of the imagination, also be nominated for biochemical underpinnings. But our minds rebel at the news that genes can induce such behavioral minutiae as hand gestures, pet-naming, and nervous giggles. According to recent research, this appears to be the case. Whether aimed at individual differences or specieswide traits, both behavioral genetics and evolutionary biology are in the business of seeking genetic paths to behavior, and both are bringing about a new perspective on the human complex.

  Therapeutic promise is not the only reason the news about gene therapy and cloning has overshadowed the news concerning behavior. The genetic insights about physical defects and dysfunctions are filling a void of knowledge or deepening existing understanding. This sort of information is welcomed by everyone. Findings about the gene-behavior dynamic, on the other hand, are overturning existing truths and demolishing assumptions upon which fifty years of psychological theory has been based. Totally different answers are emerging to questions many experts were confident had long been answered. It is this apostate cast to the behavioral findings that has caused turmoil in the academic community and provoked angry debate. It has also contributed to the early media caution in announcing the discoveries.

  THE LARGEST BODY of hard data to establish the genetic roots of behavior has come from comparisons of fraternal with identical twins and comparisons of adopted with biological siblings. For thirty years these investigations have been progressing quietly in scores of kinship studies in the United States and abroad and building a mountain of evidence of the gene-behavior relationship. Of all this research, the
most persuasive as well as the most dramatic has been an eighteen-year examination at the University of Minnesota of identical twins who were separated shortly after birth and raised in different homes. The study has examined over seventy sets of separated identical twins and more than fifty sets of fraternals. The telling results startled not only the scientific world but the Minnesota researchers themselves. This was not so much for the degree of genetic influence on traits, which has already been established by other studies, but by the highly specific nature of some genetic expressions. Some of these stories are astounding and dramatically extend the possibilities of genetic string-pulling.

  Conclusive as these overall twin findings were for many of the extensive gene-personality links, even harder scientific evidence corroborating this data is just now beginning to emerge from molecular biologists who are tracking the DNA itself to locate explicit chromosomal segments that lead to particular behaviors. While twin and adoption studies measure and compare individuals to establish genetic influence, molecular biologists can be seen as approaching human behavior “from the other end,” seeking out the individual genes that might contribute to a particular trait. Such gene pinpointing brings us much closer to interventions—enhancing, fixing, blocking. The possibilities are endless.

  After a disheartening series of near misses—studies that appeared to have located culprit genes for specific behaviors but that could not be replicated—success appeared to have arrived in January 1996. Researchers in two different research groups (one in the U.S., another in Israel) isolated a DNA fragment that was consistently longer in subjects who showed a taste for risk-taking. This appeared to be the first time a precise strand of nucleic acid was linked to a particular personality trait. The discovery was reported on the front page of the New York Times. It looked as if science had at last “seen” the bouquet of molecules that causes certain people to shoot rapids and bungee jump. As so often has happened with efforts to pinpoint behavioral genes, this finding was cast into doubt by a third study in Finland, but few in the field doubted that such specific pairings of genes and behavior were far off.

  Confusion has resulted from the two different methods of linking genes to behavior when misfires of one were mistakenly seen to negate the successes of the other. A typical example of the misunderstanding appeared in a 1994 Time magazine cover story, “Genetics, the Future Is Now.” The piece was an authoritative overview of the medical discoveries and a discussion of the social and ethical issues they evoke. The article stumbled, however, when it touched on behavior. “Studies claiming to have found genes for alcoholism,” it read, “… have not held up under scrutiny, but many people still assume such complex behaviors may be predetermined by heredity.” With the word “assume,” Time renders a belief in a genetic component to traits such as alcoholism little more than a hunch. And by the use of the word “predetermined” rather than “predisposed,” Time sets up a straw-man theory of all-powerful genes held by no behavioral geneticist.

  Twin and kinship studies have for decades established genetic components to some forms of alcoholism, depression, and many other behavioral irregularities. To accurately sum up the state of behavioral genetics research at that time, they could say that, no, scientists had not yet found the specific genes, but, yes, they knew that genes were involved. But that was knowing plenty, enough certainly to justify the millions of research dollars that have been spent in the years since seeking out specific genes. The failure to pinpoint gene-behavior tie-ups in no way weakened the hard statistical evidence of inherited predispositions from somewhere in the genome.

  In the two years since the Time article appeared, there have been major advances in gene-behavior understanding, and specific genes for specific behaviors have now been isolated. But the confusion lingers on. Reviewing Philip Kitcher’s book The Lives to Come in The New Yorker of February 12, 1996, John Seabrook wrote: “What if it turns out that there really are genes that influence intelligence, along with a variety of behavioral characteristics …?”

  To write such a sentence in a respected publication in 1996 is akin to someone writing in the New York Times, “What if it turns out the sun really is the center of the solar system …?” Although the conclusion of genetic influence over behavior has been, to a degree, inferential, the abundance of data has long since removed the issue from what-if-land.

  It is understandable that the DNA scanners have created greater excitement than the observational studies of twins and adoptees. The main reason for this preference is that zooming in on trouble-causing genes brings science much closer to therapies and remedies. But those of us rooting for broad acceptance of the new knowledge about genes and behavior see a public relations advantage as well. Astronomers might prove mathematically that Pluto is out there circling the sun, but for most people, it is much more convincing to see a photo of the elusive planet, however fuzzy.

  When scientists hold a news conference to show on a screen the gene that causes alcoholism—or depression or violence or nail-biting or child abuse—the impact on the public is sure to be far greater than the hardworking psychologist, who may have examined thousands of twins pairs, holding up charts, saying, “See, my statistics prove a genetic influence.” However powerful the numbers, this is still an abstract, circumstantial case; juries always prefer concrete, eyewitness cases.

  In animals a number of genes have been located that govern specific behaviors. Most recently a gene in female rodents was found that when blocked, turned mothers from busy nurturers into indifferent loll-abouts. The experiment had clearly isolated a good-mother gene. (Don’t have kids without it.) In humans, similar tie-ups are imminent. Since late 1994, several genetic mechanisms that cause obesity have been revealed, and many more gene-behavior couplings are sure to follow.

  As the spotlight is turning from the kinship studies with their dry statistics to the sexier molecular biologists with their promise of behavioral-gene snapshots, it should be pointed out that the searches would not have been undertaken in the first place if it were not for the psychologists who for the past thirty years, in bold defiance of their field’s prevailing orthodoxy, have been following their intuitions and searching out genetic links to behavior using the only tools at their disposal, the statistical comparisons of genetically related individuals.

  Just as Gregor Mendel only inferred the existence of genes but nonetheless developed his on-target laws in the 1860s by merely observing patterns of inheritance, so the behavioral geneticists have drawn conclusions from their studies of twins and adoptees with no idea which genes brought about the all-too-evident behavioral effects and little idea how they functioned. They pushed ahead, making no secret of their ignorance of the workings in “the black box” that sat between a gene and a trait. Although much mystery still obscures the chemical path from genes to behavior, molecular biologists have joined behavioral geneticists to demonstrate beyond any doubt that the genes-behavior paths are there.

  ON THE FACE of it, all of this may not seem too revolutionary. Everyday chitchat abounds in behavioral geneticist thinking. “She got her extravagance from her mother.” Or, “the musical talent comes from his father’s side.” Or, “he’s a crook just like his granddaddy.” Whether consciously or not, such remarks suggest DNA strings that lead to spending sprees, piano-playing, and crookedness. While we may have gut feelings of genetic transmission of personality traits—animal breeders have known about it for centuries—such thinking has been abhorrent to prevailing scientific thought for much of this century. Back-porch philosophers and animal breeders could believe whatever they wished; science knew we humans were creatures of our rearing environments. Experience and learning determined who we are, nothing else.

  This is no minor artifact of intellectual history to be tossed quickly into the bin marked “Earlier Mistakes.” The behaviorist belief in an all-powerful environment has for many decades dominated enlightened thinking and been the basis of our society’s approaches to child-rearing, education, s
ocial dysfunctions—and, of course, psychological problems. All the leading psychotherapists, from Freud to Joyce Brothers, might have disagreed about which environmental influences made you wet your bed, bite your nails, expose yourself—but none had any doubts that it was something in the environment. Always the environment. And this view is still very much with us, if more as a habit of thought than a conscious idea.

  Psychiatrist Peter Neubauer, who did his own study of reared-apart twins, tells a story of identical brothers that vividly illustrates the degree to which the environmental assumption dominated our thinking. The brothers, who were in their early thirties, had been separated at birth and raised in different countries. Both were neat and clean to a compulsive degree. When asked to explain how they had become this way, each twin traced his idiosyncrasy to his adoptive mother. One explained that his mother had also been obsessively fastidious, constantly cleaning the house, doing laundry, straightening things. He had no doubt that his tidiness came from her. The other brother, not knowing his twin’s explanation, replied without hesitation that he knew exactly why he was so neat: His mother had been a complete slob as a housekeeper. He was reacting against her.

  The men did not need training in the day’s psychology to have absorbed the behaviorist truth that the key to unusual adult behavior lay somewhere in childhood experience, in the rearing environment. There was no other possibility. Armed with that assumption, explanations were easy to come by, even if they contradicted each other.

  In the days when such behaviorist certitude prevailed, countless research projects examined how and to what degree the environment, acting alone, determined behavior. Those skewed psychological studies, which remarkably still go on, were based on the premise that one newborn was pretty much like another; the environment stamped the infants with distinctive personalities. For behaviorists, unraveling the puzzle of a particular human was simply a matter of discovering which environmental elements were the most relevant during the formative years. No one found genetic influences because no one was looking for them. Now that many are looking, they’ve found them in spades.