July 27 1998
MIND AND MATTER
New research suggests our genes do not tell
everything about the way we are, says Anjana
Ahuja
The nature of nurture
Robert Plomin shakes his head as he picks
through his salade niçoise and admits he is
embarrassed: "It's unbelievable. Everywhere we
look, we find that genes have a substantial
influence. I'm embarrassed by how important
genetics is turning out to be."
This is a peculiar thing for him to say, because
Professor Plomin is one of the most eminent
behavioural geneticists in the world. Even if you
haven't heard his name, you will know of his
research.
Previously based at the University of Colorado
and now deputy director of the Social, Genetic
and Developmental Psychiatry Research Centre
at the Institute of Psychiatry in London, his
achievements include the discovery of a gene
for intelligence (or, more correctly, a gene which
accounts for a tiny fraction of the variation in
intelligence). It was revealed last week that his
team of researchers had found a gene for
language ability in young children.
You might have thought this would plant him
firmly on the nature side of the nature v nurture
debate in the discussion of how genes and
environment shape individual personality. But
Professor Plomin adopts an unexpected stance.
He thinks the pendulum has swung too far in his
favour: "Once, everybody thought environment
was all-important, and the only thing that
mattered was the way you were brought up.
Then behavioural genetics came along and it
seemed that genes was everything and
environment was nothing. Actually, environment
is terribly important too.
"Take schizophrenia. Identical twins, who have
identical genes, have a 50 per cent concordance
on the condition. That means that if one twin
develops it, the other has a 50 per cent chance
of developing it. Since their genes are the same
whether they develop schizophrenia or not, it
must be to do with environment. It's an amazing
finding."
Further support for the significance of
environment comes from a new study by
Professor Plomin of 720 American families,
each featuring a mother, father and two
adolescent children. According to conventional
belief, children brought up in the same home
share the same environment. So one would
expect natural brothers and sisters to share
many traits. However, they can be poles apart in
personality. But Professor Plomin and his
colleagues discovered that the issue of
environment was more complex than previously
thought. For one thing, it turned out that parents
often treated each child differently, or were
perceived as treating each child differently. This
implied that each child in the family was being
nurtured in a slightly different environment.
"For example, some adolescents felt their
parents were more antagonistic to them than to
their brother or sister. So you think: 'This
explains why one child develops antisocial
behaviour.' But when you see a video of the
parent and child together, you realise the parent
is reacting to the child's aggressive behaviour.
How can a parent be loving when their child is
acting like a jerk? Genes are affecting the family
environment."
It raises the possibility that people choose or
shape their surroundings according to their
genes. This has led Professor Plomin to think
about nature v nurture not as a tug-of-war
between disparate influences but as part of one
phenomenon. He has renamed it the "nature of
nurture".
Professor Plomin also thinks that experiences
outside the home for each sibling may be
significant in moulding character traits. "It's a
shot in the arm for the environmentalists. It
opens up opportunities for studying
gene-environment correlations."
Some might suggest that, if environment is so
important, why should we pour in millions of
pounds teasing out genetic influences, especially
if individual genes have such minuscule effects?
"Behavioural genetics is a scientific target but it's
also a practical target," he says.
For example, society could provide preventive
therapy for those at risk from alcoholism or drug
abuse: "Alcoholism wrecks lives. But we wait to
see who develops it and then step in with cures
that don't work. If we have the genetic markers,
we should use them to alleviate suffering.
Preventive medicine is the future."
The concerns raised over possible pre-natal
testing to screen out certain diseases do not
bother him unduly. "When the amniocentesis
test was developed, people thought it was the
end of the world. But women chose to have it.
Why would a woman do it unless she was
prepared to contemplate abortion? If mothers
were selecting for certain traits, that would be
dodgy."
What about discrimination by employers and
insurance companies against those found to be
at risk of developing disease? "That would not
be ethical but I am sure we will have laws to
protect against it."
He thinks most people, provided there are
preventive treatments available, would prefer to
know their genetic destiny, despite the
drawbacks.He also objects to the idea that
geneticists are part of a right-wing conspiracy to
engage in dodgy social engineering. (Professor
Plomin, who grew up in inner-city Chicago, is a
Labour supporter.) He elects not to study topics
such as the differences in intelligences across
race and class. "I'm too chicken to do stuff like
that," he says. What especially bugs him is when
the word "Nazi" is mentioned in the same breath
as behavioural genetics, as happened on the
Today programme last week. "Some of the
media seem to want to protect the public from
the wicked scientists," he sighs. "It's a very
condescending view and I am willing to bet that
the man in the street isn't that worried.
"Geneticists have this anecdote about parents,
which I think has a measure of truth about it:
when parents have one child, they think the
kid's behaviour is down to how they are bringing
them up. When they have a second child and
they start noticing big personality differences,
they begin believing in genetics."
In a way, he says, the ethical concerns
surrounding the field of behavioural genetics
constitute a badge of honour. "All great
advances in science have problems," Professor
Plomin reflects. "So it's terrific that we have
given ethicists so much to think about."
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