Journal of Abnormal Child Psychology

, Volume 33, Issue 2, pp 219-229

First online:

Understanding the Covariation Among Childhood Externalizing Symptoms: Genetic and Environmental Influences on Conduct Disorder, Attention Deficit Hyperactivity Disorder, and Oppositional Defiant Disorder Symptoms

  • Danielle M. DickAffiliated withDepartment of Psychiatry, Washington University in St. Louis
  • , Richard J. VikenAffiliated withDepartment of Psychology, Indiana University
  • , Jaakko KaprioAffiliated withUniversity of Helsinki & National Public Health Institute
  • , Lea PulkkinenAffiliated withUniversity of Jyväaskylä
  • , Richard J. RoseAffiliated withDepartment of Psychology, Indiana UniversityDepartment of Psychology, Indiana University Email author 

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Conduct disorder (CD), attention deficit hyperactivity disorder (ADHD), and oppositional defiant disorder (ODD) are common childhood externalizing disorders that frequently co-occur. However, the causes of their comorbidity are not well understood. To address that question, we analyzed data from > 600 Finnish twin pairs, who completed standardized interviews at age 14. Behavior genetic methods were used to examine how genetic/environmental factors contribute to each disorder’s symptoms and to their covariation. We found significant genetic effects on each disorder with only modest evidence of shared environmental influences. Our data suggest the comorbidity among CD, ADHD, and ODD is primarily explained by shared genetic influences; however, each disorder was also under unique genetic influence, supporting the distinction of each disorder.


attention deficit hyperactivity disorder conduct disorder oppositional defiant disorder genetics externalizing disorders