The Inventory of Callous-Unemotional Traits (ICU) in Children: Reliability and Heritability

Callous-unemotional (CU) traits comprise the core symptoms of psychopathy, yet no study has estimated the heritability of CU traits in a community sample of children using an instrument designed solely to assess CU traits. The current study uses data from 339 twin pairs aged 9–14 to examine the reliability and heritability of the parent-report Inventory of Callous-unemotional Traits (ICU) at two assessments approximately 3 weeks apart. Time-specific measurement error was taken into account to obtain a more accurate estimate of the heritability reflecting the latent liability to CU traits. Test–retest reliability was 0.84 and heritability at visit 1 was 39%. The heritability of the latent liability to CU traits was 47%. This latent liability contributed 79% of the variance in ICU score at visit 1 and visit 2. This is the first study to account for measurement error while examining the heritability of CU traits, furthering our understanding of psychopathy in children.