 Paths estimates are expressed as the proportion of variance accounted for by common or specific aetiological factors. For callous-unemotional, 00% of overall genetic influences are due to shared factors and 00% due to trait specific factors. For social interaction, 00% of overall genetic influences are due to shared factors and 00% due to trait specific factors. For social communication, 00% of overall genetic influences are due to shared factors and 00% due to trait specific factors. Dotted arrows indicate a non-significant path estimate. A~c~ = common genetic factors; E~c~ = common non shared environmental factors; A~s~ = specific genetic factors; C~s~ = specific shared environmental factors; E~s~ = specific non shared environmental factors. h^0^ = proportion of variance on the trait explained by additive genetic influences; c^0^ = proportion of variance explained by shared environmental influences; e^0^ = proportion of variance explained by non-shared environmental influences.](pone.0000000.g000){#pone.0000000.g000}  For callous-unemotional, social interaction and social communication difficulties