Comorbidity among childhood disruptive behavioral disorders is commonly rep
orted in both epidemiologic and clinical studies, These problems are also a
ssociated with early substance use and other markers of behavioral disinhib
ition. Previous twin research has suggested that much of the covariation be
tween antisocial behavior and alcohol dependence is due to common genetic i
nfluences. Similar results have been reported for conduct problems and hype
ractivity, For the present study, an adolescent sample consisting of 172 MZ
and 162 DZ twin pairs, recruited through the Colorado Twin Registry and th
e Colorado Longitudinal Twin Study were assessed using standardized psychia
tric interviews and personality assessments, DSM-IV symptom counts for cond
uct disorder and attention deficit hyperactivity disorder, along with a mea
sure of substance experimentation and novelty seeking, were used as indices
of a latent behavioral disinhibition trait. A confirmatory factor model fi
t to individual-level data showed a strong common factor accounting for 16-
42% of the observed variance in each measure, A common pathway model evalua
ting the genetic and environmental architecture of the latent phenotype sug
gested that behavioral disinhibition is highly heritable (a(2) = 0.84), and
is not influenced significantly by shared environmental factors, A residua
l correlation between conduct disorder and substance experimentation was ex
plained by shared environmental effects, and a residual correlation between
attention deficit hyperactivity disorder and novelty seeking was accounted
for by genetic dominance, These results suggest that a variety of adolesce
nt problem behaviors may share a common underlying genetic risk, Am. J. Med
. Genet. (Neuropsychiatr. Genet.) 96:684-695, 2000, (C) 2000 Wiley-Liss, In
c.