How the nature vs. nurture debate shapes public policy and our
view of ourselves
by Wray Herbert.
in longer form, appeared in Newsweek
every week there is a report of a new gene for one trait or another.
Novelty seeking, religiosity, shyness, the tendency to divorce,
and even happiness (or the lack of it) are among the traits that
may result in part from a gene, according to new research. This
cultural shift has political and personal implications.
the personal level, a belief in the power of genes necessarily
diminishes the potency of such personal qualities as will, capacity
to choose, and sense of responsibility for those choices --if
it's in your genes, you're not accountable. It allows the alcoholic,
for example, to treat himself as a helpless victim of his biology
rather than as a willful agent with control of his own behavior.
Genetic determinism can free victims and their families of guilt
--or lock them in their suffering.
the political level, biological determinism now colors all sorts
of public policy debates on issues such as gay rights, health
care, juvenile justice, and welfare reform. The effort to dismantle
social programs is fueled by the belief that government interventions
(the nurturing side in the nature-nurture debate) don't work very
well --and the corollary idea that society can't make up for every
unfortunate citizen's bad luck. It's probably no coincidence that
the biologizing of culture has accompanied the country's shift
to the political right, since conservatives traditionally are
more dubious about human perfectability than are liberals.
1993 National Research Council study, for example, reported strong
evidence of genetic influence on antisocial personality disorder,
but it also noted that many genes are probably involved. Getting
from those unknown genes to an actual act of vandalism or assault,
or a life of barbaric violence, requires at this point a monstrous
leap of faith.
Yet it's a leap that many are willing to make. When geneticist
Xandra Breakefield reported a possible genetic link to violent
crime a few years ago, she immediately started receiving phone
inquiries from attorneys representing clients in prison; they
were hoping that such genetic findings might absolve their clients
of culpability for their acts.
and emotions. Just two decades ago, the National Institute of
Mental Health was funding studies of economic recession, unemployment,
and urban ills as possible contributors to serious emotional disturbance.
A whole branch of psychiatry known as "social psychiatry"
was dedicated to helping the mentally ill by rooting out such
pathogens as poverty and racism. There is no longer much evidence
of these sensibilities at work today. NIMH now focuses its studies
almost exclusively on brain research and on the genetic underpinnings
of emotional illnesses.
decision to reorder the federal research portfolio was both scientific
and political. Major advances in neuroscience methods opened up
research that wasn't possible a generation ago, and that research
has paid off in drugs that very effectively treat some disorders.
But there was also a concerted political campaign to reinterpret
mental illness. A generation ago, the leading theory about schizophrenia
was that this devastating emotional and mental disorder was caused
by cold and distant mothering, itself the result of the mother's
unconscious wish that her child had never been born. A nationwide
lobbying effort was launched to combat such unfounded mother blaming,
and 20 years later that artifact of the Freudian era is entirely
discredited. It's widely accepted today that psychotic disorders
are brain disorders, probably with genetic roots.
this neurogenetic victory may be double edged. For example, family
and consumer groups have argued convincingly that schizophrenia
is a brain disease like epilepsy, one piece of evidence being
that it is treatable with powerful antipsychotic drugs. Managed-care
companies, however, have seized upon the disease model, and now
will rarely authorize anything but drug treatment: it's efficient,
and justified by the arguments of biological psychiatry. The American
Psychiatric Association just this month issued elaborate guidelines
for treating schizophrenia, including not only drugs but an array
of psychosocial servicesservices the insurance industry
is highly unlikely to pay for.
search for genes for severe mental disorders has been inconclusive.
Years of studies of families, adoptees, and twins separated at
birth suggest that both schizophrenia and manic-depressive illness
run in families. But if that family pattern is the result of genes,
it's clearly very complicated, because most of the siblings of
schizophrenics (including half of identical twins, who have the
same genes) don't develop the disorder. Behavioral geneticists
suspect that several genes may underlie the illness, and that
some environmental stress--perhaps a virus or birth complications--also
might be required to trigger the disorder.
of desire. It would be a mistake to focus only on biological explanations
of psychopathology; the cultural shift is much broader than that.
A generation ago, the gay community was at war with organized
psychiatry, arguing (successfully) that sexual orientation was
a lifestyle choice and ought to be deleted from the manual of
disorders. Recently the same community was celebrating new evidence
that homosexuality is a biological (and perhaps genetic) trait,
not a choice at all.
going on, it's clear that this new mistrust of genetic power is
consonant with what science is now beginning to show. Indeed,
the very expression "gene for" is misleading, according
to philosopher Philip Kitcher, author of The Lives to Come. Kitcher
critiques what he calls "gene talk," a simplistic shorthand
for talking about genetic advances that has led to the widespread
misunderstanding of DNA's real powers. He suggests that public
discourse may need to include more scientific jargon, not a lot,
but some, so as not to oversimplify the complexity of the gene-environment
interaction. For example, when geneticists say they've found a
gene for a particular trait, what they mean is that people carrying
a certain "allele,"a variation in a stretch of DNA that
normally codes for a certain protein, will develop the given trait
in a standard environment. The last few words, "in a standard
environment," are very important, because what scientists
are not saying is that a given allele will necessarily lead to
that trait in every environment. Indeed, there is mounting evidence
that a particular allele will not produce the same result if the
environment changes significantly; that is to say, the environment
has a strong influence on whether and how a gene gets "expressed."
emerging view of nature-nurture is that many complicated behaviors
probably have some measure of genetic loading that gives some
people a susceptibility, for schizophrenia, for instance, or for
aggression. But the development of the behavior or pathology requires
more, what National Institute of Mental Health Director Stephen
Hyman calls an environmental second hit." This second hit
operates, counter-intuitively, through the genes themselves to
"sculpt" the brain. So with depression, for example,
it appears as though a bad experience in the world, for example,
a devastating loss, can actually create chemical changes in the
body that affect certain genes, which in turn affect certain brain
proteins that make a person more susceptible to depression in
the future. Nature or nurture? Similarly, Hyman's own work has
shown that exposure to addictive substances can lead to biochemical
changes at the genetic and molecular levels that commandeer brain
circuits involving volition, and thus undermine the very motivation
needed to take charge of one's destructive behavior. So the choice
to experiment with drugs or alcohol may, in certain people, create
the biological substrate of the addictive disorder. The distinction
between biology and experience begins to lose its edge.
proliferation of "official" psychiatric disturbances
since 1952, when the first "Diagnostic and Statistical Manual
of Mental Disorders'' (DSM) was published has increased from 60
to 145 (2nd edition, 1968) to 410 (4th edition, 1994). Cynics
think therapists are spreading a wider net to90 catch more clients,
but new brain imaging techniques and genetic studies have converged
on the likelihood that these all may reflect variations in brain
function. ``ultimately,'' says Dean Hamer, a leading behavioral
geneticist at the National Cancer Institute. . .``it might mean
that we're all a little bit crazy.''
1997 book ``Shadow Syndromes,'' by psychiatrist John Ratey of
Harvard Medical School and Catherine Johnson of the National Alliance
for Autism Research argues that all sorts of quirky behaviors
are actually mild mental illnesses.
"The athletic megastar who is as cool as ice in the championship
game but explodes at a bar is not just a spoiled brat; he is beset
by intermittent rage disorder. Men who are unable to talk about
their feelings suffer ``from an unrecognized adult form of attention
deficit disorder'' (ADD). Mild ADD also marks the business titan
who can't file his taxes on time. The deadbeat dad, who dotes
on his children when they visit but who can't seem to remember
to send the child-support checks, is neither a louse nor someone
chafing at an unfair custody arrangement. He has mild ``environmental
dependency syndrome'': he can't focus on his kids unless he's
with them. And the woman who can't abide a husband who fails to
help with the house and kids once the two of them return from
their jobs may suffer from ``a very mild form of obsessive-compulsive
disorder.'' Call it Mental Illness Lite."
many people have occasional and temporary symptoms of mental illness--from
sadness to exuberance bordering on mania--``it's very difficult
to say where mental illness shades into normalcy,'' admits Dr.
Mark Olfson of Columbia University. ``And that poses real questions
for treatment: when should you prescribe antidepressants? In fact,
they've exploded in use and are now prescribed for subclinical
new book, ``Making Us Crazy,'' by social scientists Herb Kutchins
and Stuart Kirk, blasts the DSM for being scientifically unsound,
swayed by politics (homosexuality is a mental illness; no, it
isn't) and pathologizing everyday behaviors like holding a grudge
or worrying about public speaking. ``The psychiatric bible has
been making us crazy--when we are just human,'' they argue."
absolutely going to be the case that geneticists will come to
the aid of psychiatrists in this debate,'' says Stanford University
neuroscientist Robert Sapolsky. "The idea of a continuum
represents a major cognitive breakthrough for genetics. It suggests
that a middling genetic load [of mental-illness genes] gives you
a personality disorder, a lighter one gives you a personality
quirk and a still lighter one gives you mainstream America.''
found the first hints that mental illness comes in mild forms
when they examined relatives of seriously ill people. "So-called
schizoid personalities, who are extremely withdrawn, are commoner
in families of schizophrenics,'' says Dr. Jonathan Benjamin of
Ben Gurion University in Israel. ``And awkward social behavior
is more frequent in the biological parents of autistic children.''
That suggests that while the patient has many mental-illness genes,
the relatives have only a few, and thus have ``shadow syndromes.''
offers the classic illustration. Schizophrenics have less gray
matter in the frontal cortex, the seat of higher thought, says
psychiatrist Tyrone Cannon of the University of Pennsylvania.
And in the hippocampus, which helps run memory and emotion, cells
are out of place. People with mild schizophrenia, whose symptoms
are not severe enough to keep them socially isolated, have mild
versions of these brain abnormalities. People with severe schizophrenia,
who are unable to distinguish fears and fantasies from reality,
have severe versions. ``Our twins study suggests that people with
two genes out of a hypothetical 10 might have only subtle changes
in brain structure and function,'' says Cannon. ``But as you increase
the number of genes you pass over the threshold to clinical significance.''
"LAST YEAR . . . Researchers discovered an abnormally long
version, or allele, of a gene on chromosome 11 (humans have 23
pairs of rod-shaped chromosomes, along which genes are strung
like pearls). The allele was found more often in heroin addicts
than in nonaddicts. The job of this gene is to produce a receptor--a
sort of molecular docking site--for the brain chemical dopamine.
Here's where the continuum comes in: the long version of the gene
is also common in mentally healthy people who exhibit ``novelty-seeking''
behavior, according to research groups in Israel and at the National
Institutes of Health in 1996. Such people tend to be impulsive,
fickle, excitable, quick-tempered and extravagant; they seek thrills
and feel exhilarated in novel situations. They are the world's
race-car drivers and its explorers. This gene is only one of an
estimated 10 or so that determine novelty-seeking, explains Ben
Gurion's Benjamin. Someone with 2 or 3 of the 10 might be a little
impulsive. Someone with all 10 might be a risk freak--or a heroin
just the last two years, researchers have discovered several genes
that may account for personality quirks and, in combination with
other genes, trigger mild or full-blown mental illness: In 1996
researchers led by NCI's Hamer identified a gene on chromosome
17 that contributes to neuroticism. This catchall term includes
being anxious and sometimes depressed, hostile and impulsive.
The gene comes in short and long forms, Hamer explains in ``Living
With Our Genes,'' a book due in March. It makes what is called
a transporter, a protein that sweeps away the brain chemical serotonin
from between neurons. Serotonin, Hamer believes, causes anxiety
and depression. The short form of the gene makes less transporter,
which is less effective at removing serotonin. One would therefore
expect a connection: short gene, more serotonin, more anxiety.
That's what the researchers found--the short form of the gene
is more common in people who are neurotic (as determined by questionnaires).
But this gene accounts for only a tiny amount of the differences
in people's genetically determined degree of neurotic behavior.
Hamer estimates it at 7 to 9 percent. In other words, there are
other neuroticism genes. Having few or many could mean the difference
between glancing anxiously at the clock when your teenager is
out past her curfew . . . and being Woody Allen.
In 1997 researchers linked a gene on chromosome 22 to obsessive-compulsive
disorder. OCD is marked by intrusive, upsetting thoughts (the
``O''), like not being able to let go of the idea that you forgot
to turn off the oven, and repetitive behaviors that interfere
with daily life (the ``C''), like constant hand-washing. The purported
OCD gene makes a sort of bio-vacuum cleaner--an enzyme that gets
rid of brain chemicals after they have carried a signal between
neurons. Everyone has this enzyme, but the OCD version makes such
a wimpy version of it that the brain chemicals keep delivering
the same infernal message over and over--a nagging ``did you turn
off the oven?'' Again, several genes are thought to cause OCD.
Someone with all of them might be so tied up in worries and obsessions
as to be dysfunctional. Someone with one or two might keep a superneat
research suggests that milder forms of OCD arise from milder brain
abnormalities, too. PET scans, which detect regions of high activity
in the brain, have shown that a circuit running from the orbital
frontal cortex--the bottom front of the brain, which acts as a
sort of error-detection system--is hyperactive in OCD patients,
finds Jeffrey Schwartz of UCLA. ``It gives you the feeling of
being stuck in gear,'' he says. In people with depression but
not OCD, just the outer rim of the orbital frontal cortex is running
full tilt. ``These people have problems getting ruminations out
of their mind,'' says Schwartz. ``It's not a true obsession, but
a milder thing''--with a milder brain abnormality.
December, researchers at Johns Hopkins University traced a gene
for manic-depression to chromosome 18. That makes at least five
genes associated with this disease. ``It may be that if you have
only one gene,'' says Dr. Francis McMahon, who led the team, ``you
might be more susceptible to mood elevations that let you meet
deadlines through a burst of activity, or lead your business team
across the finish line. The gene may be overrepresented among
artists and creative types.'' Actor Robin Williams has described
his deep depressions; any fan can see his mania. But someone with
all five manic-depression genes might be too buffeted by mood
swings to function. Says neuroscientist Dr. Samuel Barondes of
UC, San Francisco, ``Maybe having one of these genes is really
good for you, but having all of them makes you crazy.''
associated with mental illness might, in fact, keep society supplied
with the personality types it needs. People with schizotypal personality
disorder, explains Stanford's Sapolsky, gravitate toward solitary
lives. They are lighthouse keepers and fire-tower rangers. Those
with a touch of OCD are the dogged employees who don't let go
of a task until it is complete. Long ago, they may have been shamans
and witch doctors and, perhaps, the men who established religious
rituals. Who else could have thought up a Hindu ritual of washing
the left hand 10 times, the right one 7 and both 5 more at the
beginning of the day? The visions of Joan of Arc, the prophet
Muhammad and Saint Paul are suggestive of hallucinations produced
by temporal-lobe epilepsy. And in 1990 researchers in Minnesota,
studying identical twins, calculated that religious belief is
50 percent genetic. Mercifully, they refrained from calling it
the God Gene.
IF NEUROSCIENTISTS FIND brain lesions linked to holding grudges
or spending too much time on the Internet, and even if geneticists
find stretches of DNA linked to being aloof or persistent, that
will not prove that biology is destiny. For one thing, the structure
and activity patterns of the brain reflect experience, not just
the biology one is born with. The 40-year-old who has no interest
in his lover's feelings may indeed have ``bad brain chemistry.''
But that chemistry could be the product of a bad relationship
with his father, social pressures to be emotionally distant--even
a traumatic first date. And Schwartz's work with OCD patients
has shown that they can overcome their ``brain lock'' by ``willfully
activating healthy circuits to predominate over the unhealthy
ones,'' he says. Even genes that affect behavior by acting on
the brain may determine our fate only in part. In a recent study,
biologists found that baby rats whose mothers lick them have physically
different brain structures from those whose mothers don't. The
differences lie in regions that respond to stress. Licked rats
handle it better than deprived rats do, suggesting that life's
experience shapes the brain even when it comes to a trait as basic
idea that eccentric behaviors may be mild forms of mental illness
is so new that its implications for society are unclear. But some
scientists already worry about stigmatizing people who carry even
a few genes for serious mental illness. Will couples count their
respective ``crazy genes'' before they have children--or abort
fetuses with too many of them? Will prospective mates demand to
look at each other's brain scans? What will that do to the world's
supply of artists and dreamers, adventurers and inventors? ``If
we discover that there are many genes associated with mental illness,''
says Hopkins's McMahon, ``and that at least some of them are pretty
common, it could make us realize that we're all in the same boat.''
Which suggests that when everyone is crazy, no one will be. So
pundits will still get to poke fun at the notion that road rage,
gourmand syndrome and other nouveaux disorders are real mental
illnesses. But as genetic and neuroscience discoveries add support
to the idea that something real, something physical, underlies
these and other seemingly trivial ills, it will be harder to laugh.