16 December 2013

Dr John Gillott By

Appeared in BioNews 735

The House of Commons Education Committee is currently investigating 'Underachievement in education of white working class children'. At a session on 4 December it took evidence from a range of experts, including geneticist Professor Robert Plomin, an internationally recognised authority on the genetics of children with learning disabilities in particular and behaviour genetics in general.

The whole session makes for interesting viewing, but with his recent study grabbing headlines, the exchanges between Plomin and the Committee are particularly worth a listen (from 11.07 in the video).

Plomin began by suggesting that rather than talking about IQ or intelligence, which tends to raise red flags, the Committee should instead focus its attention on the heritability of educational attainment as measured by exam scores. 25 minutes later, prompted by Dominic Raab MP, he concluded the meat of his contribution by venturing into wider debates on genetics, intelligence and socioeconomic status (about which he has also published very recently).

Committee members were clearly impressed - and occasionally wowed, it seems - by Plomin's knowledge, authority and argument. But they were also quizzical, and some gave the distinct impression that they didn't think Plomin was addressing the issues that matter. Implicitly, some Committee members said 'So what? We already know that pupils vary greatly in aptitude (and indeed appetite, following Plomin's distinction) and educators take this into account'. Leading educationalist Michael Reiss makes this point explicitly and strongly in the Guardian, and this has also been debated on BBC World News.

Secondly, many Committee members made it clear that they are concerned with whatcould be, more than with what is. They want to know how they can make a difference. As Chair Graham Stuart MP put it (I paraphrase slightly): 'your [Plomin's] numbers are system-wide, but how much elasticity is there in that school effect? You're saying the effect is 20 percent typically, but how much when there is an exceptional school? How much is there to play for?'

Shortly after this point in proceedings, Plomin worried about heading down the rabbit hole, or whether indeed he already had:

'The science of this is so clear I feel like Alice in Wonderland or something. It's completely the elephant in the classroom sort of thing. Nobody in education wants to take on the fact that genetics accounts for more variation than everything else put together... When the DNA chips come out... that can identify people's DNA differences, it's going to really change things fast'.

Alongside his desire to explain, it is not hard to detect a certain amount of frustration on Plomin's part. Perhaps because of this, some of his evidence to the Committee veered towards the hyperbolic. His reference to the use of DNA chips in the classroom is one example. He told Committee members that he expected these to come into play in five years' time or shortly thereafter. This seems highly unlikely to me.

As Sarah Norcross has pointed out, 'the idea of "personalised medicine", which uses our understanding of genetics in order to tailor treatment to individuals, has been promoted for several decades with only very modest success to show for it and brings problems with equity in accessing it. The idea of tailoring education to individuals based on our understanding of their genetics deserves to be treated with, if anything, an even greater degree of scepticism'.

A second example is the issue he closed on: genetics, intelligence and socioeconomic status (SES). In educational mode himself, Plomin told the Committee that 'if you realise social mobility you will increase heritability'. Pausing briefly to ask 'Does everyone see that?' he went on to state that 'heritability is an index of social equality'. Then, in a little more detail:

'It could be that instead of high parent-offspring correlations for inter-generational mobility being an index of lack of social mobility, it might be an index of social mobility. I know that's hard to get your head around right away'.

At this point the camera revealed some blank faces. Shortly afterwards, the overtly genetic aspects of the witness session were drawn to a close, before they strayed too far into Boris Johnson shaken-cornflake-box territory. In some ways it's a shame they didn't dwell longer, for it seems to me that in this case hyperbole is in danger of leading to outright false claims.

As all young logicians know, A implies B does not mean B implies A (e.g. all dogs are mammals but not all mammals are dogs). Plomin is right to say that high social mobility, all things considered, means high parent-offspring correlation. But the reverse does not hold, logically and, I'd argue, empirically in many contexts – imagine a rigid caste or feudal society to see this. In reality it is very hard to measure the heritability of SES, and high heritability for SES is consistent with both high and low social mobility. To be generous to Plomin, the relationship is as he said in the longer extract, with the emphasis on 'could' and 'might'. To be less generous, the bald statement 'heritability is an index of social equality' is flat out wrong.

In conclusion: Plomin and colleagues make some very good and important points, and I have little doubt that many in education and education policy don't like discussing genetics, or at least this aspect of genetics. But Plomin and colleagues need to develop their arguments and they certainly need to rein in the hyperbole if they want to make headway in political and policy worlds.

Committee members and educationalists make some good points themselves, of which those I highlighted are just two. Simply emphasising the fact that genetics contributes around 50 percent of the variation and claiming a genetic basis for the fact that we all attempt to shape our environments to suit our appetites and our abilities are not killer points in themselves.