Here (a bit late) is my latest Wall Street Journal column, on
In the debate over whether our fates
as individuals are ruled by nature or nurture-that is, by innate
qualities or personal experience-one of the most baffling features
is the way the nurture advocates manage to cast themselves as the
great foes of determinism. "Genes don't determine who we are," they
insist-all the while positing that environmental causes
often do. Remember how some Freudians tried to blame
autism, schizophrenia and even homosexuality on the way parents
treated their children? True, they claimed these effects were
treatable, but so are many genetic problems. I wear glasses to
correct a partly genetic tendency to myopia.
Nor has environmental determinism
escaped moral stain. When Soviet agriculture was forced to obey
crank theories that environmental conditioning rather than breeding
could determine the frost-resistance of wheat-not coincidentally
echoing the notion that human nature could be remade by
communism-the result was famine.
Yet the idea persists that paying
attention to genetic factors amounts to fatalistic resignation,
whereas focusing on an individual's upbringing affirms freedom and
opportunity. Thus do certain quarters welcome any chance to knock
genes off their pedestal, including a new set of discoveries that
go by the name of epigenetic inheritance.
If your father ate fatty food, it
turns out, you may be prone to diabetes (so long as you are a rat).
This result, recently announced by scientists in Sydney, is
surprising because it has long been accepted that mammals are
descended from the sperm, not the bodies, of their fathers. One
early geneticist even cut off the tails of 1,500 rats over 20
generations to prove that their offspring did not inherit docked
Yet there's already a hint that the
Australian result will apply to people. In Sweden, paternal
grandsons of men who experienced a particular 19th-century famine
in their youth had lower rates of diabetes and cardiovascular
disease. So, apart from its possible medical significance, the fat
rats suggest a new form of parental influence, probably through
small gene-like RNA molecules smuggled into sperm.
If this result stands up, does it
turn evolutionary theory and genetic determinism on their heads? If
we can inherit some effects of lifestyle, outside the genetic
structure, does this free us from the tyranny of genes?
Hardly. It's hard to feel liberated
if we get diabetes because of something our
parents did before our birth rather than something
they were. There are other tyrannies than genetic
The word "epigenetic" is decades old
and refers to the switching on and off of genes during development.
Some genes get locked down when no longer needed in particular
tissues. Cancer cells, for example, lock down tumor-suppressor
genes that would normally halt their spread.
One of the chief locking mechanisms
is "methylation," the attachment of a chemical block to part of the
gene sequence. In the diabetic Australian rats, one gene was nearly
twice as active as normal because this process was much reduced.
And what makes the proteins that insert or remove these chemical
blocks? Our genes. It looks as if some of those proteins, or the
RNAs that trigger the manufacture of those proteins, are carried
over into the next generation in the sperm or egg.
The new results are evidence that
genes are sensitive to experience. But we knew that. From suntan to
memory, lots of bodily things happen because genes are activated by
environmental triggers: Genes switch on and off in your brain in
response to what you perceive, think and do. That's why the old
nature-nurture dichotomy is so misleading. Genes are our slaves as
much as our masters.
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