Fig. 1.

Histograms of estimates of heritability of gene expression. a Classical twin modeling-based estimates of each gene. Based on the resemblance of MZ and DZ twin pairs, the variance of the expression of each gene was decomposed into additive genetic, common (or shared) environmental, and unique environmental variance. A standard ACE model was used, assuming dizygotic twins have an average IBD sharing of 0.5 across the genome, and monozygotic twins share an IBD of 1. Parameters were estimated by maximum likelihood (ML). b IBS-based h²_cis estimates of each gene, i.e. variance explained by a GRM created for each cis-window of a gene, defined by the coordinates of a gene with 250 kilobase (kb) flanking area on each side. c IBS-based h²_res estimates of each gene, i.e. variance explained by a GRM including closely related individuals for the autosomes with all off-diagonal elements below 0.05 set to 0