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Are genes really the reason more poor kids do badly at school?

What matters more when it comes to intelligence: nature or nurture? Brain image from

A news report recently informed readers that the reason children from poorer backgrounds struggle is due to genetic “inherited abilities”.

According to the article, a new Productivity Commission report had ranked genetics ahead of other factors when explaining variations in school achievement and life chances. But the news article didn’t get it quite right; it was a simple interpretation that overestimated the influences of genetics on human intelligence.

But when it comes to putting too much stock in “nature over nurture” and human intelligence, this is really nothing new.

Born or made?

The Productivity Commission report looked at the origins of “deep and persistent disadvantage”. The aim was to better understand (and rectify) some citizens’ incapacity to “do well” in contemporary Australia.

The report cited various social and familial reasons behind disadvantage that make it more likely that children from poor families will not perform well in school, are more likely to drop out and less likely to go on to further education or training.

It also discussed possible genetic differences between social classes as causative of disadvantage. In other words, the report included class-based inherited differences in intelligence as being at least a partial explanation of why some do better in school and in life than others.

But can we really blame genes, even in part, for “deep and persistent” disadvantage?

Measuring intelligence as an occupation began in France in the early years of the 20th century. The development of mass schooling raised many issues one of which was the learning difficulties experienced by a minority of children.

French psychologist Alfred Binet was commissioned to develop a test that would help identify children who were unable to thrive in ordinary classrooms but needed special educational assistance. The Binet-Simon Intelligence Test did this very well and set the mould for intelligence tests that followed, including establishing the convention that “IQ” has an average of 100. Significantly, Binet himself regarded his test as measuring current performance only and certainly not future attainment or “potential” of any sort.

Despite Binet’s beliefs about the malleability of intelligence when intelligence testing was taken up by psychologists in the US, attitudes to cognitive ability rapidly changed. Intelligence came to be seen as innate, genetically based and immutable. Tests were used to “prove” the inferiority of African Americans and non-Anglo immigrants (including the Irish) to the US. Advocates of “racial inferiority” still vehemently defend a view of intelligence as genetically caused and immutable.

Moving intelligence

The idea that an IQ score represents a measure of an unchanging human characteristic has been subjected to testing – and falsification – by a gigantic natural experiment. The enthusiasm for testing intelligence has resulted in the amassing of vast quantities of data on the intellectual characteristics of whole populations, stretching across now several decades.

Rather than intelligence remaining static over the time that it has been measured the average intelligence of populations in a range of countries has gone steadily up, at the rate, in the US, of 0.3 points per year, resulting in a gain of 30 points since trends have been tracked. Academic James Flynn has studied the phenomenon and it is named after him: The Flynn Effect.

These astonishing gains have even been found on intelligence tests that are supposedly free of the effects of experience and “pure” measures of innate ability, such as the Raven’s progressive matrices test. Also, the gains have occurred across all segments of the “intelligence” range, so that those who scored at the low end have improved as much as those from the middle and the top.

The steady increase in the average result on intelligence tests has meant that these have to be regularly “re-normed” to keep the average at 100. If earlier norms are used the results can be extraordinary: for example, if the current population was tested using norms from the 1950s, 75% would be classified as gifted.

The news is also good for group differences. While disadvantaged groups - including African Americans - do indeed score lower on average on intelligence tests than advantaged groups, their average score not only been increasing it has done so more quickly than the white average score. This has meant that the gap between white Americans and African Americans has been shrinking.

If the difference is genetically based then this would not happen. The time span involved is simply too brief to allow for major changes in genetic endowment.

Blaming the victim

There now exists a great deal of evidence that intellectual performance is highly influenced by the environment, including the family learning environment. The compulsion to include unsupported speculation about class differences in genetic endowment explaining disadvantage is lamentable.

It is likely to not only incense those from groups stigmatised as “inferior” but also to license “blaming the victim” when children from disadvantaged groups fail to achieve well at school.

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