I’ve been doing some thinking recently about the findings of behavioural geneticists and their implications for education policy. For instance, a study of more than 10,000 twins found that GCSE results are nearly 60 per cent heritable. (This research, by Robert Plomin, was first revealed in The Spectator.) So genetic differences between children account for almost 60 per cent of the variation in their GCSE results, with the environment, such as the schools they go to, accounting for less than 40 per cent.