Vol. 7, No. 4, 2001 Page 6
ARE WE HARDWIRED? THE ROLE OF GENES IN HUMAN BEHAVIOR
By William R. Clark and Michael Grunstein
Oxford University Press, 2000
$24 +S&H (hardback)
Authors William R. Clark and Michael Grunstein obviously have a
remarkably extensive background in genetics. Even their list of over 200
references, conveniently listed by chapter, covers 17 pages. Clark is
Professor Emeritus in the Department of Molecular, Cell and
Developmental Biology at UCLA, and Grunstein is Professor of
Biological Chemistry, also at UCLA.
Research reports from single cell organisms to the latest twin studies
are summarized. It is a fascinating story, told in easy to read language.
Genetic influences on aggression, learning, memory, sexual preference,
human "sixth sense," neurotransmitters, free will, substance abuse, and
considerably more are analyzed.
The "nature vs. nurture" question is discussed in detail. The authors'
answer is that both are important, and that one interacts with—not
opposes—the other. They present scientific evidence that combinations
of genes have much more impact on any one behavior than has usually
One wonders how long it will be before science, using genome
mapping, will learn how to improve all human behavior. Don't guess the
answer before you read this book; the time may arrive sooner than you
Quotes from ARE WE HARDWIRED? by Clark and
- In the laboratory, rats and mice have been selectively bred for many
generations to create strains that are fearful or aggressive. These strains
pass on their personality differences each time they breed. No one
seriously questions the role of genes in the development of animal
behavior, or of inheritance in passing these traits from one generation to
the next. Yet we are reluctant to acknowledge a similar role of genes in
guiding human behavior.
- Genetic variation may affect not only our responses to the environment,
but our very perception of it in the first place.
- Surprisingly, numerous studies of twins, and both biological and adopted
siblings, have shown that shared home experiences have a minimal effect
in shaping the personalities of children....The similarities in siblings
reared together appear to derive mostly from their shared genetic
inheritance, and not from the home environment.
- The type of aggressive behavior associated with low serotonin is
impulsive, rather than premeditated, aggression.
- We can destroy our children's natural mental abilities, but we cannot
improve them. We may wish it were different, and intuitively we may
think it should be different, but at the present time there are simply no
data suggesting that it is. We can provide a secure and culturally
enriched environment that will allow each child to optimize his or her
innate abilities, but we cannot fundamentally alter these abilities.
- [A] parent and an adopted child are no more likely to score the same on
an IQ test than two randomly selected unrelated individuals, even after
many years of a close family relationship. A parent and a biological
child, on the other hand, are much more likely to score close to one
another—even when the child is adopted out at birth, and the parent and
child are tested only later in life.
- Heritability patterns for substance abuse correlate strongly with
heritability of other personality factors. Among individuals seemingly
predisposed to substance abuse there is a higher than normal frequency
of individuals manifesting impulsive behaviors, such as attention deficit
disorders, thrill seeking, aggressiveness, and gambling, among others.
There is also a strong correlation of substance abuse with negative
emotionality, including personality parameters such as neuroticism,
anxiety, and alienation.
- [A]lthough language, cognition, and culture make all human behaviors
more complicated to dissect, there is no reason to believe that the basic
causes underlying human aggression are different from those we see in
other animals, or that genes play a greater or lesser role in regulating
aggressive behavior in humans than in other animals.
- Each of us must struggle to maximize the genetic hand we have been
dealt, played in the context of the environment into which we are born,
against a certain level of indeterminacy we must somehow learn to bring
under control. It is this struggle that defines us, and makes us human.