Genetic and Parental Environmental Influences on Callous-Unemotional Traits of Twins in Childhood

Abstract

Despite growing interest in the developmental origins of callous-unemotional (CU) traits, limited evidence exists from non-Western contexts on the relative contributions of genetic and parental environmental factors. The present study addresses this gap by examining the genetic and environmental architecture of CU traits among twins during early childhood. A descriptive and analytical twin research design was employed in the Hisar district of Haryana state. The sample comprised 50 twin pairs (N=100) aged 6–9 years, including monozygotic (MZ) and dizygotic (DZ) twins identified through snowball sampling. Data were collected from parents using the Inventory of Callous-Unemotional Traits (ICU) and the Alabama Parenting Questionnaire (APQ). Statistical analyses included descriptive measures, z-test, chi-square test, and heritability estimation using Falconer’s formula. The results revealed significant mean differences between MZ and DZ twins in callousness (Z = 2.28*) and overall CU traits (Z = 2.59*), indicating higher levels among monozygotic twins, whereas differences in uncaring (Z = 1.21) and unemotional (Z = 0.06) traits were non-significant. The heritability estimate (h² = 78.0%) suggests a strong genetic basis for CU traits, with environmental factors accounting for 22.0% of the variance. Furthermore, significant associations were observed between CU traits and inconsistent discipline (χ² = 9.95*), corporal punishment (χ² = 7.89*) and overall parental environment (χ² = 5.61*) and found the role of adverse parenting practices. The study contributes novel empirical evidence from a rural Indian context, emphasizing the interaction of genetic predispositions and modifiable environmental factors. The findings underscore the need for targeted, family-based interventions aimed at reducing harsh and inconsistent parenting to mitigate CU traits during early childhood.