Peter K. Dearden
I am loath to write this post, not only because it is New Year’s Day and I am in Melbourne, but also because the subject matter touches some raw nerves. The problem is I have been increasingly angry at the way genetics is beginning to be used to inform policy in education. Not so much here in New Zealand, but in the UK there are worrying signs that genetics is being used as an argument to de-invest in education. Given that NZ often follows the UK, I wanted to point out a few problems with what has been reported (for example here, here and here).
The facts are that measures of ‘intelligence’ have been shown to be highly heritable. This is a difficult statement to make because it sums up a great deal of research which is all flawed in some respect. The first problem is one of measurement, intelligence is measured as a ‘g-factor’, a measure of general ability, which is based on a number of tests, but is often thought similar to IQ. Any measurement of intelligence is flawed, as testing will only address some of the attributes that might count as ‘intelligence’. That such tests are flawed, and need to be treated with extreme scepticism is demonstrated most clearly by the ‘Flynn effect’, a general increase in IQ scores since 1930 first identified by Prof Jim Flynn, one of New Zealand’s National Treasures.
Such tests, however, measure something, and the inheritance of that something can be studied. Most of the studies to address this question have been made using twins. Twins are a wonderful way to study genetics in humans because of the different degrees that monozygotic (identical) twins and dizygotic (fraternal or sororal) twins share their genomes. Monozygotic twins share 100% of their genomes, dizygotic on average 50%. By comparing the number of monozygotic twin pairs in which a particular trait is present in both twins (concordance) with dizygotic twins you can get a measure of the heritability of that trait.
Unfortunately heritability isn’t a simple measure of the genetic contribution to a trait. The differences in phenotype between individuals in a population are due to a combination of genes, environment and gene-environment interactions. Heritability is a measure of just the genetic contribution to a trait, but this is very difficult to disentangle from the environment. This is because the environment can affect the heritability. This sounds odd, but lets take a simple example. Measures of the heritability of smoking have been made (for example see here ) that show that initiation of smoking is heritable. There are genes that, presumably, predispose you to smoking. But if you live in a world with no access to cigarettes etc, then that heritability must drop to 0. Smoking is heritable but ONLY in a specific environment.
To remove the environmental influence in twin studies, researchers have compared twins raised together with twins raised apart; a way of removing the ‘shared environment effect’. If twins raised apart show high concordance, then that similarity must be genetics, not environment. The problem is that these are people, and twins raised apart are rare, and often the agencies that control adoption will try and match the environments of a pair of adopted-out twins. These studies, therefore are flawed. This doesn’t mean they are useless, but it important to know the difficulties with them before we use them to inform policy.
In more recent years (for example here) modern genetic techniques that circumvent some of the problems with twin studies have been sued to show that ‘g’ is highly heritable. Such studies have their own suite of problems, but I think we can accept that ‘g’, a measure of something related to intelligence, is highly heritable.
So what does that mean for education? It seems likely that this means that some differences in educational attainment is related to genetic factors. Does that mean that there is little point in investing in education because achievement is heritable? The answer is most certainly not.
Again we have to worry about the subtle interplay between genes and environment. The heritability of a trait is affected by the environment. No amount of ‘good genes’ is going to improve your educational achievement if you have no access to education. While those with ‘good genes’ might do better than those with ‘bad genes’ in such a situation, it is the environment (education) that is key to the outcome. If you think about it, the genetic differences in educational achievement will become MORE apparent the more similar the environment (educational quality) becomes. Surely then the argument must be that the education must be of the highest quality for EVERY student to ensure that everyone gets the chance to demonstrate their ‘good genes’. Part of this ‘highest quality’ may be the use of genetics to help identify aptitudes, or best modes of learning, for students, but genetics is no argument for a reduction in investment in education.
Policy should be informed by science. But we as scientists need to make sure that that science is properly interpreted before it is used. In this case, all I can see here is genetics being used as an argument to support the continuance of a ruling elite (For example, see this speech by the current mayor of London). Education is too important for ALL of society to be lavished only on those thought to be ‘genetically superior’.