Cross-twin within-trait and cross-trait correlations, stratified by zygosity and gender.

<p>Key points </p><p></p><p>-</p><p>Difficulties in appropriate social interaction are characteristic of both children with autism spectrum disorders and children with callous-unemotional traits.</p><p></p><p>-</p><p>Experimental studies suggest that the nature of atypical social cognition that characterises these two profiles is not identical. However, ‘empathizing’ difficulties have been reported in both groups.</p><p></p><p>-</p><p>Our findings indicate that both social and communication impairments and callous-unemotional traits show modest phenotypic overlap. Aetiological influences accounting for individual differences on each domain were predominantly independent.</p><p></p><p>-</p><p>Although both children with high levels of ASD traits and children with high levels of callous-unemotional traits exhibit difficulties in appropriate social behaviour, the underlying drivers of these impairments are predominantly distinct.</p><p></p><p></p><p></p>-<p>Difficulties in appropriate social interaction are characteristic of both children with autism spectrum disorders and children with callous-unemotional traits.</p>-<p>Experimental studies suggest that the nature of atypical social cognition that characterises these two profiles is not identical. However, ‘empathizing’ difficulties have been reported in both groups.</p>-<p>Our findings indicate that both social and communication impairments and callous-unemotional traits show modest phenotypic overlap. Aetiological influences accounting for individual differences on each domain were predominantly independent.</p>-<p>Although both children with high levels of ASD traits and children with high levels of callous-unemotional traits exhibit difficulties in appropriate social behaviour, the underlying drivers of these impairments are predominantly distinct.</p><p>Cross-trait correlations are below the diagonals; within-trait correlations are on the diagonals. Abbreviations: CU = callous-unemotional; SI = Social interaction; SC = Social communication.</p