The above link, if you listen to it 16mins and 30 seconds in from the start, is a BBC radio interview with Prof Plomin, talking about the high heritability of scholastic attainment. This high heritability is because of the high heritability of intelligence as a causal variable, and presumably also because of the heritability of associated personality variables conducive to conscientious study.
A direct heritability estimate for scholastic achievement is a considerable step forward. Two thirds of the variance is impressive. It equals the correlation between intelligence and reading found by Rutter and Yule in their Isle of Wight studies 40 years ago, a result which pre-figures this one, and is closely related to it.
Plomin’s findings led to confused questions about whether it is worth while paying a lot of heed to educational interventions when so much of the variance is genetic. In strict terms, the heritability estimate is based on the relative contribution of genetic variation, but only given a particular social and educational environment. For example, it assumes that the UK’s relatively wealthy and peaceful society functions as before, with free health services, free schools, subsidised benefits and all the rest of it. Removing such advantages would boost the contribution of the environment, to the extent that even lower quality schooling and living standards would depress the level of achievement. Bad circumstances boost the amount of variance accounted for by the environment. Good circumstances reduce the environment’s contribution to variance.
That is, we expect a poorer school environment would reduce scholastic attainment. We cannot be sure how much is transmitted culturally by families, even when school systems are very poor. There is no getting away from the finding that if two thirds of the variance can be explained by individual differences in the genetic code, then the remaining third is an unknown blend of other family differences (bright parents helping their children with their homework, for example), peer group influences, and the school effect, such as it is. Some of the apparently great differences between different schools and different teaching methods may well be unsubstantiated. Perhaps a benefit of understanding this would be for parents to be more relaxed about school league tables, and concentrate on helping their child learn at the pace and in the style best suited to them.
The teacher asked to comment on the radio programme feared, quite understandably, that genetic screening of children would lead to self-confirming prophecies, and well they might. That danger must be balanced against the larger danger that a relatively standard form and pace of instruction fails to meet the needs of children with widely differing intellectual demands. Most children quickly work out the braininess of their classmates, if only because every lesson gives them plentiful evidence of human differences, so labelling is there even if teachers avoid it.
Another reason for listening to the interview is to hear a researcher keeping calm and explaining the main findings without exasperation. In the wish to avoid labelling children, many UK schools have also avoided tailoring their teaching to the needs of pupils, particularly the brighter ones. Plomin, the first in his family to get a university education, and aware from an early age that he needed to get books from the Chicago public library to feed his curiosity, must have been tempted to champion the cause of bright children, and the benefits of fitting education to their intellectual needs. He kept his cool. Calmness is required if we are to climb the mountain of fear and rejection which surrounds individual differences, particularly those differences which allow one person to think five times faster than another.