There also exists some heterogeneity within the diagnostic construct of conduct disorder and our sample may differ from Dick et al., 2006 in some of these respects. For example, some CD youth demonstrate life-course persistent symptoms, while others have symptoms limited to adolescence (Moffit, 1993); unfortunately, such categories are difficult to distinguish in a cross sectional study of youth. Also, CD symptoms in the DSM-IV include varied behaviors, ranging from relatively more minor/non-aggressive offenses such as breaking curfew to serious illegal behaviors, such as forced sex; thus, one youth may meet a three symptom threshold for CD by engaging in non-aggressive, rule breaking behaviors, while another engages in highly aggressive and cruel behaviors; the two would not be distinguished by the phenotype employed here. Finally, some have argued that underlying temperament or personality traits (rather than DSM criteria which emphasize behavior), such as unemotionality and interpersonal callousness, should be given more attention (i.e. Frick & Morris, 2004).
