A Monozygotic Twin Differences Study of Nonshared Environmental Influence on Adolescent Depressive Symptoms


  • The authors would like to thank the twins and their parents in the GENESiS1219 Twins Project for making this study possible.

concerning this article should be addressed to Holan Liang, Child & Adolescent Psychiatry Department, Institute of Psychiatry, P.O. Box 085, De Crespigny Park, London SE5 8AF, U.K. Electronic mail may be sent to h.liang@iop.kcl.ac.uk.


The monozygotic (MZ) twin differences method was used to examine nonshared environmental aspects of the association of parenting (punitive and constructive discipline), negative life events (independent and dependent), and peers (antisocial and prosocial) with adolescent depressive symptoms in terms of sequelae, risk, and maintaining factors. Two self-report booklets were completed by 328 MZ twin pairs aged 12–19 years, 6 months apart. Increased punitive discipline and negative life events were found to be relevant nonshared environmental factors that followed depression. Negative life events were the only factor that had a direct nonshared environmental association with concurrent depressive symptoms in adolescents independent of previous depressive symptoms, and all other study variables.