Twin study raises doubts about the relevance of "grit" to children’s school performance

Grit is in vogue. US psychologist Angela Duckworth's TED talk on grit is one of the most popular recorded. And her forthcoming book on the subject, subtitled "the power of passion and perseverance" is anticipated to be a bestseller. On both sides of the pond, our governments have made the training of grit in schools a priority.

To psychologists, "grit" describes how much perseverance someone shows towards their long-term goals, and how much consistent passion they have for them. It's seen as a "sub-trait" that's very strongly related to, and largely subsumed by, conscientiousness, which is known as one of the well-established "Big Five" main personality traits that make up who we are.

The reason for all the interest in grit, simply, is that there's some evidence that people who have more grit do better in life. Moreover, it's thought that grit is something you can develop, and probably more easily than you can increase your intelligence or other attributes.

But to a team of psychologists based in London and led by behavioural genetics expert Robert Plomin, the hype around grit is getting a little out of hand. There just isn't that much convincing evidence yet that it tells you much about a person beyond the Big Five personality traits, nor that it can be increased through training or education.

Supporting their view, the researchers have published an analysis in the Journal of Personality and Social Psychology of the personalities, including grit, and exam performance at age 16 of thousands of pairs of twins. Some of the twins were identical meaning they share the same genes, while others were non-identical meaning they share roughly half their genes just like non-twin siblings do. By comparing similarities in personality and exam performance between these two types of twin, the researchers were able to disentangle the relative influence of genes and the environment on these measures.

The main finding is that the participants' overall personality scores were related to about 6 per cent of the variation seen in their exam performance. Grit specifically was related to just 0.5 per cent of the differences seen in exam performance. Given the small size of this relationship, the researchers said "we believe that these results should warrant concern with the educational policy directives in the United States and the United Kingdom."

Also relevant to the hype around grit, the researchers found that how much grit the participants had was to a large extent inherited (about a third of the difference in grit scores were explained by genetic influences), and that none of the difference in grit was explained by environmental factors that twin pairs shared, such as the way they were raised by their parents and the type of schooling they had (this leaves the remaining variance in grit either influenced by so-called "non-shared environmental factors" – those experiences in life that are unique to a person and not even shared by their twin who they live with – or unexplained). This is a disappointing result for grit enthusiasts because it suggests that the experiences in life that shape how much grit someone has are not found in the school or the home (at least not for the current sample). Bear in mind, though, that this doesn't discount the possibility that a new effective home- or school-based intervention could be developed.

The researchers concluded that once you know a child's main personality scores, knowing their amount of grit doesn't seem to tell you much more about how well they'll do at school. This study doesn't rule out the idea that increasing children's grit, if possible, could be beneficial, but the researchers warned that "more research is warranted into intervention and training programs before concluding that such training increases educational achievement and life outcomes."

Further reading

Rimfeld, K., Kovas, Y., Dale, P., & Plomin, R. (2016). True Grit and Genetics: Predicting Academic Achievement From Personality. Journal of Personality and Social Psychology DOI: 10.1037/pspp0000089