By Charles Craig
While biotechnology and pharmaceutical companies race to find disease genes and drugs to offset them, identifying genes for normal behavioral traits, such as happiness, nurturing and intelligence, remains a more academic exercise.
Much of the reason has to do with the complexity of behavior, but it also has to do with the controversial aspects of delineating genetic differences for such traits.
Irving Gottesman, a psychology professor at the University of Virginia, in Charlottesville, said he intersperses cautionary "footnotes," warning against extreme interpretations, in discussions of behavioral genetics, a field he has studied since 1959.
"In the future," he told BioWorld Today, "and I'm not quite sure how far that is; it's not 100 years, but more like five or six years, we will have the knowledge to talk about groups of people that have a characteristic gene for [such behavior as] thrill seeking, or sensation seeking."
Researchers will be able to say, Gottesman observed, a certain "percent of individuals with this gene"--and he hesitates here for a cautionary footnote about not reading too much into his example--"may engage in breaking the speed limit."
However, a specific genetic variation is not considered a forecaster of individual behavior in the same way a gene for cystic fibrosis is for that disease. Too many other genes and the environment are major factors.
"Even with mental disease states, such as schizophrenia and bipolar disorder, there are identical twins where one is discordant for the disease, meaning environment must play a role," Gottesman said. "If I had 100 such pairs, I may be able to say 50 of them may get the disease."
Gottesman was co-author of a paper in the June 1997 issue of the American Journal of Human Genetics (AJHG) titled: "Behavioral genetics '97: ASHG statement; recent developments in human behavioral genetics: past accomplishments and future directions."
He described the article as a "white paper" on the status of research into genetic links to behavior.
Another co-author, Stephanie Sherman, professor of genetics and psychology at Emory University, in Atlanta, said the article was written "by committee" as a statement from the American Society of Human Genetics (ASHG), declaring the science of behavioral genetics "valid," but warning researchers they must be wary of how they report their findings and how they may be interpreted.
"Genes must play some role. But how much is environment and how much is genetic?" Sherman said.
A goal of behavioral genetic research, she said, is not to create drugs to tweak genes to achieve some cultural ideal of normality. "The more we learn about genetics, the more we learn about environment," Sherman observed.
Appreciate Differences Before Changing Them
She used the example of reading ability. "There's tremendous difference in how we read and what would help us read better," Sherman said. "Studies show genes are involved in reading," and such information, she suggested, could be used to structure school reading programs based on what genetic traits are malleable.
But before public policy decisions take into account individual genetic differences, Sherman said, "We have to appreciate those differences. There will always be gene-environment interaction. How do you work the environment to make the best use of genetic make-up?"
In the AJHG paper, the authors wrote: "Only a few decades ago, psychologists believed that characteristics of human behavior were almost entirely the result of environmental influences. These characteristics now are known to be genetically influenced, in many cases to a substantial degree. Intelligence and memory, novelty seeking and activity level, and shyness and sociability all show some degree of genetic influence."
While claims have been made for discovery of specific genes linked to normal behavioral traits, Gottesman and his colleagues said many researchers question those findings because they have yet to be duplicated.
What have been discovered are gene regions, Gottesman said. "We don't have candidate genes with known neurochemical properties," he observed. "But we have found enough evidence to keep requesting grants."
Another co-author of the AJHG article is John Loehlin, professor emeritus of psychology at the University of Texas, Austin. He describes research into normal behavioral traits --as opposed to finding mental disease genes--"as an interesting exercise. We should know about it to the extent that we know now behavior is influenced by genes."
However, Loehlin added, "If there is a scientific consensus [on how the information should be used], it is that there are no immediate implications for these discoveries."
In their conclusions on the continuation of research into behavioral genetics, the authors said, "Individual differences in behavioral traits, including personality and abilities, are of wide public interest and of considerable social importance, even when differences fall within the nonpathological range. Public knowledge, program design and policy development should rest not on popular myths, but on findings from the best available science."
However, fashioning public policy on behavioral genetics may prove among the most sensitive of subjects.
In a perspective piece in the June 6, 1997, issue of Science, Gottesman wrote, "The journey of behavioral geneticists from their reputation as determinists [genes determine behaviors] to the one they now strive for as probablists [genes determine the likelihood of behaviors] has been an uphill struggle."
Gottesman told BioWorld Today, "I'm cautiously optimistic about the relationship between scientific data on genetic aspects of normal and abnormal behavior and policy decisions."
The caution, he said, stems from potential critics who would play on public fears that "all this will lead to Nazi-style eugenics or to identification of children who have predisposition to certain behaviors."
And those concerns, he added, have elevated sensitivities to bioethics among researchers to the point that forums on those issues are commonplace at scientific conferences.
Despite his wariness, Gottesman observed, "This is an exciting time to be alive and be involved in this area"--the confluence of psychology, genetics, pharmacology and neuroscience. *