Rethinking Environmental Contributions to Child and Adolescent Psychopathology A Meta-Analysis of Shared Environmental Influences

• Published in: Psychological bulletin Vol. 135; no. 4; pp. 608 - 637
• Main Author: Burt, S. Alexandra
• Format: Journal Article
• Language: English
• Published: Washington, DC American Psychological Association 01-07-2009
• Subjects: Adolescent; Adolescents; Adoption; Adoption - psychology; Adult and adolescent clinical studies; Age Differences; Anxiety; Anxiety-Depression; Attention Deficit Disorder with Hyperactivity - genetics; Attention Deficit Disorder with Hyperactivity - psychology; Attention Deficit Disorders; Behavior Disorders; Behavioral Genetics; Biological and medical sciences; Child; Child clinical studies; Child development; Children; Children & youth; Depression (Psychology); Diseases in Twins - genetics; Diseases in Twins - psychology; Environment; Environmental aspects; Environmental Influences; Externalization; Female; Gender Differences; Genetics; Human; Humans; Hyperactivity; Internal-External Control; Internalization; Male; Medical sciences; Mental disorders; Mental Disorders - genetics; Mental Disorders - psychology; Meta Analysis; Miscellaneous; Nature Nurture; Parenting - psychology; Phenotype; Psychology. Psychoanalysis. Psychiatry; Psychopathology; Psychopathology. Psychiatry; Research Methodology; Risk Factors; Siblings; Social Environment; Statistical Analysis; Systematic review; Twin Studies as Topic; Twins; nonshared environment; shared environment; externalizing; internalizing; Human; Adolescent; Mental disorder; Environmental factor; Review; Psychopathology; Child; Metaanalysis
• ISSN: 0033-2909; 1939-1455
• DOI: 10.1037/a0015702

Behavioral genetic research has concluded that the more important environmental influences result in differences between siblings (referred to as
nonshared
;
e
2
), whereas environmental influences that create similarities between siblings (referred to as
shared
;
c
2
) are indistinguishable from zero. However, there is mounting evidence that during childhood and adolescence,
c
2
may make important contributions to most forms of psychopathology. The aim of the meta-analysis was to empirically confirm this hypothesis. The author examined twin and adoption studies (
n
= 490) of internalizing and externalizing psychopathology prior to adulthood. Analyses revealed that
c
2
accounted for 10%-19% of the variance within conduct disorder, oppositional defiant disorder, anxiety, depression, and broad internalizing and externalizing disorders, regardless of their operationalization. When age, informant, and sex effects were considered,
c
2
generally ranged from 10%-30% of the variance. Importantly,
c
2
estimates did not vary across twin and adoption studies, suggesting that these estimates reflect actual environmental influences common to siblings. The only exception was attention-deficit/hyperactivity disorder, which appeared to be largely genetic (and particularly nonadditive genetic) in origin. Conceptual, methodological, and clinical implications of these findings are discussed.