Twin correlations indicate genetic influences on self-control, grit, and school performance, with cross-trait cross-twin correlations higher in MZ than DZ twins¶

Claim · All claims
Evidence · 1 study (2 entries) · associational r2–r3 · q3
Currency · newest study 2023 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q3 i? MZ twin correlations for school performance, self-control, and grit (0.809, 0.715, 0.751) exceed DZ correlations (0.419, 0.276, 0.176), suggesting an ADE model for self-control and grit. → Kevenaar 2023 q3 i? In the ADE model, most phenotypic variance is genetic: broad-sense heritability of school performance is 0.793 (76.8% A, 2.5% D), and about 73% of grit variance is genetic. → Kevenaar 2023 (2)

Evidence¶

Kevenaar 2023¶

Kevenaar, S. T., van Bergen, E., Oldehinkel, A. J., Boomsma, D. I. & Dolan, C. V. (2023). The relationship of school performance with self-control and grit is strongly genetic and weakly causal. npj Science of Learning, 8:53. https://doi.org/10.1038/s41539-023-00198-3

q3 · i? · associational · r2

Saturated-model MZ and DZ correlation matrices (Table 1), conditional on covariates sex, SES, and rater and corrected for censoring. The article notes cross-trait cross-twin correlations are "higher in MZ than DZ, suggesting genetic correlations between the traits".

"The MZ twin correlations in Table 1 for school performance, self-control, and grit equal 0.809 (95% CIs: 0.788 –0.928), 0.715 (95% CIs: 0.685 –0.716), and 0.751 (95% CIs: 0.722 –0.778), respectively"

Kevenaar 2023 (2)¶

Kevenaar, S. T., van Bergen, E., Oldehinkel, A. J., Boomsma, D. I. & Dolan, C. V. (2023). The relationship of school performance with self-control and grit is strongly genetic and weakly causal. npj Science of Learning, 8:53. https://doi.org/10.1038/s41539-023-00198-3

q3 · i? · associational · r3

ADE twin model (Model 2) variance decomposition (Table 2). For school performance, "76.8% is attributable to additive genetic factors" and 2.5% to dominance factors (broad-sense heritability 0.793); rater effects ranged from 21.2% (grit) to 0.2% (self-control).

"the standardized variance of grit, conditional on the covariates (SES, sex, and rater), is expressed in proportions as follows 0.179 (A), 0.556 (D), and 0.265 (E)"

Discussion¶

Learner Variables¶

• Personality Traits — predictor: learners who differ on it differ in outcomes

Related Claims¶

• Direct causal effects of self-control and grit account for only 4.4% of school performance variance, with self-control the stronger causal predictor — related
• Teacher-rated self-control and grit jointly explain 28.4% of the variance in school performance in standard phenotypic regression — related