> The heritability of conscientiousness facets and their relationship to IQ and academic achievement
> Genetic research has shown that intelligence makes a major contribution to the heritability of educational achievement. However, we show that other broad domains of behavior such as personality and psychopathology also account for genetic influence on GCSE scores beyond that predicted by intelligence. Together with intelligence, these domains account for 75% of the heritability of GCSE scores.
> The high heritability of educational achievement reflects many genetically influenced traits, not just intelligence
> Our findings confirmed positive associations between IQ and the facets of Competence and Dutifulness (ranging 0.11–0.27), with academic achievement showing correlations of 0.27 and 0.15 with these same facets and 0.15 with Deliberation. All conscientiousness facets were influenced by genes (broad sense heritabilities ranging 0.18–0.49) and unique environment, but common environment was judged unimportant.
While academic achievement western societies still isn't as much determined by individual skill as many people would like to believe, it's worse in the countries the immigrants come from, and additional factors like language barriers and discrimination (intentional, structural or even accidental) render the idea of inheritability quite useless.
Another problem is that studies have identified environmental factors which influence intelligence much more than any known individual genetic factors. For example infections with Malaria or other parasites, but also the duration and quality of school attendance.
You will notice that none of the "twins raised apart" studies include such factors, because virtually no children in western societies have these problems.
And that's why the impact of the education system and socioeconomic factors on academic achievement are vastly underestimated, especially because people keep bringing up these inheritability studies.