VARIOUS TEXTS: Nature vs nurture – What are the latest genetic findings?

The nature-nurture­debate remains a hardy perennial* for parents: why are siblings so ­different to each other? The latest evidence makes it look increasingly likely that genes play little or no part. Many naturally incline to the cosy answer that "it's a bit of both" but the evidence I presented eight years ago in my book "They F*** You Up: How to Survive Family Life" (by Oliver James) already showed that, even if you accepted the validity of studies of identical twins (which I do not) on which nearly all claims about the role of genes were based, they did not ­support this idea. For the vast majority of common traits, such as sociability, memory or creativity, heritability* was closer to a quarter.

Then came the findings of the Human Genome Project* in 2001. To the horror of geneticists, Craig Venter, one of the main researchers, pointed out that the fact that we only have about 25,000 genes meant psychological differences between individuals could not be much determined by them – "our environments are critical*," he concluded.

Initially, geneticists disputed this, but the last decade has seen an ­increasingly rapid retreat. After many millions of pounds and thousands of studies, attempts to identify genes that have much effect on our psychology have failed. The most distinguished researchers now admit that it is ­ extremely unlikely that there are single genes for major mental illnesses such as schizophrenia. After decades of hearing from such people that there would be a gene for almost everything, I admit to having felt a twinge of smugness*.

Their fallback position* is that it's lots of different genes interacting together that matters, but that much remains to be seen. And now comes the first sign that the geneticists may eventually have to admit defeat.

This month's editorial of the Journal of Child Psychology and Psychiatry is entitled "It's the environment, stupid!". The author, Edmund Sonuga-Barke, confesses that "serious science is now more than ever focused on the power of the environment … all but the most dogged* of genetic determinists have revised their view of the primacy of genetic factors."

In Sonuga-Barke's own field, ADHD, he states that "even the most comprehensive genome- wide scans ­ available, with thousands of patients using ­hundreds of thousand of genetic ­markers … appear to account for a relatively small proportion of disorder expression." In plain English, genes hardly explain at all why some children have ADHD* and not others.

Another fallback is to claim that genes create vulnerabilities* that environments may or may not cause to be expressed. This position took a massive blow at the end of last year. Some studies had shown that people with a particular gene variant were more likely to become depressed if they were maltreated as children: the variant created a vulnerability. This was all but disproved*.

An analysis of the 14,250 people whose DNA* had been mapped in 14 studies showed that those with the variant were not at greater risk of depression than those without it. Nor were they more likely to be depressed when the variant was combined with childhood maltreatment.

..... Obviously, genes confer* fundamentals, such as the capacity for humour or anger, but how much and how we express these is in response to our particular family situation, for which we need flexibility, not predetermination. If genes play little part in how our children turn out, that is incredibly good news. Unlike our DNA, we can do something about them.
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Source: The Guardian, Saturday 23 January 2010 by Oliver James

hardy perennial - Dauerthema
heritability - Erblichkeit
Human Genome Project - The Human Genome Project ( H.G.P.) was an international scientific research project with a primary goal to determine the sequence of chemical base pairs which make up DNA and to identify and map the approximately 20,000–25,000 genes of the human genome from both a physical and functional standpoint.
critical - ausschlaggebend, entscheidend
twinge of smugness - Anflg von Spießigkeit
fallback position - Rückzugsposition
dogged - hartnäckig
ADHD - Attention-Deficit Hyperactivity Disorder = Aufmersamkeitsdefizit
vulnerability - Schwachstelle
to disprove - widerlegen
DNA - Bezeichnung für den chemischen Aufbau der Erbinformation. Die Bausteine der DNA (engl.: Desoxyribonucleic acid) sind die so genannten Nukleotide, die sich aus jeweils einem Zucker (Desoxyribose), einem Phosphat und einer Base zusammensetzen.
to confer - übertragen, erteilen

1. Generally describe what the author's point of view is on the impact of genes.
2. How did the HG Project of 2001 change the so-called geneticists' opinion?
3. According to Sonuga-Barke's study, do genes account for ADHD symptoms in children?
4. What do the latest studies show about the connection between gene variants and possible fits of depression?
5. What about the relation of our capacity of humour or anger and our genes?
6. What is your opinion on the impact of our genes and the environment respectively on human abilities, particularly our intelligence?

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