Results from the age 12 data suggest that the hyperactivity/impulsivity subscale was more strongly related to the conduct disorder composite (rH/I-CD = .64) than the attention problems subscale (rATT-CD = .46). Factor loadings for the substance use and novelty-seeking measures were quite similar across these two subscale models. The latent behavioral disinhibition factor was somewhat more heritable in the attention problems model (a2 = .66) compared with the hyperactivity/impulsivity model (a2 = .57), but this difference was not statistically significant. Likewise, the genetic correlation between behavioral disinhibition and response inhibition was higher for the attention problems model (rA = −.65) as compared with the hyperactivity/impulsivity model (rA = −.41). However, based on the 95% confidence intervals for these estimates, this difference was also nonsignificant. Results from the age 17 data showed a similar pattern to those from age 12 in terms of the relationships among the observed variables. Although the genetic correlation between behavioral disinhibition and response inhibition was higher for the attention problems model (rA = −.71) than for the hyperactivity/impulsivity model (rA = −.46), the heritability estimates of
