Appendix 1—figure 13. Prediction accuracy for years of schooling, for individuals with 0 or 1 full sibling.

(A) The y-axis shows the prediction accuracy, measured as incremental $R^2$, in prediction sets stratified by participants’ number of siblings, using a polygenic score for years of schooling based on a GWAS performed using individuals who reported to have exactly 1 sibling. The x-axis shows the p-value threshold for inclusion of a SNP in the polygenic score when based on a pruning and thresholding approach. Last points on the x-axis correspond to a polygenic score model based on the LDpred approach (Vilhjálmsson et al., 2015) with a prior probability of 1 on loci being causal. Points are values based on 10 iterations of resampling estimation and prediction sets. Thick horizontal lines denote the mean values. (B–E) Comparison of the distribution of Townsend deprivation index (B) the age distribution (C), the proportion of males (D), and mean years of schooling (± 2 SD) between individuals who reported having no sibling and those who reported having 1 sibling. The two sets have somewhat different distributions of ages (or possibly come from somewhat different birth cohorts), a feature that could contribute to the patterns seen in panel A, but are otherwise similar with respect to the other features considered.