Children show substantial differences in literacy and numeracy skills from early primary school, with long-term consequences for education and later life outcomes. Correlational studies repeatedly showed associations between children’s educational performance and their non-cognitive skills, including grit and self-control. Yet, these findings may be confounded by stable individual differences and shared genetic and environmental factors. Here, we investigated the developmental interplay between children’s grit and self-control and their literacy and numeracy skills throughout primary school, leveraging two approaches that aim to strengthen causal inference.
In longitudinal twin data from the Netherlands Twin Register (up to N = 41,677 individuals), we analysed teacher-reported grit and self-control, and parent- and teacher-reported literacy and numeracy at ages 7, 10, and 12 years. Correlations between literacy and numeracy and non-cognitive skills were moderate to strong (r = .27 – .48). However, random-intercept cross-lagged panel models and monozygotic co-twin control analyses did not point towards a clear pattern of causal effects: Cross-lagged and within-twin pair effects were small (β = .05 – .12), in part non-significant, and inconsistent across traits, measurement ages, and modelling approaches.
Overall, findings highlight robust associations between learning and non-cognitive skills, but suggest that these are largely explained by stable individual differences due to common genetic and environmental effects across development.
Alexandra Starr is a postdoctoral researcher at Vrije Universiteit Amsterdam, Netherlands. Her research examines why children differ in their learning ability, and how these differences develop over time. She applies genetically sensitive approaches, including twin-family designs and polygenic scores to study how genes and environments jointly shape learning. A central focus of her work is investigating whether ‘environmental’ factors, such as parental behaviours and household chaos, causally shape children’s development or partly reflect genetic confounding.