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A study of problem behaviors in 10- to 15-year-old biologically related and unrelated international adoptees
E J van den Oord1, D I Boomsma, F C Verhulst
1Department of Child and Adolescent Psychiatry, Sophia Children's Hospital-Erasmus University, Rotterdam, The Netherlands.
Insights
Nonshared environmental factors significantly impact child problem behaviors. While genetics influence externalizing behaviors, they do not affect internalizing behaviors in adoptees, contrasting with twin study findings.
Area of Science:
- Behavioral genetics
- Developmental psychology
- Child psychiatry
Background:
- Understanding the interplay of genetic and environmental factors is crucial for addressing child problem behaviors.
- Previous research, primarily twin studies, has provided insights into these influences.
- International adoptee samples offer a unique perspective on genetic and environmental contributions.
Purpose of the Study:
- To investigate genetic and environmental influences on various problem behaviors in international adoptees.
- To compare findings with existing twin study data.
- To examine the role of sibship size and sex differences.
Main Methods:
- Utilized parental ratings of child problem behaviors via the Child Behavior Checklist (CBCL).
- Analyzed data from biological siblings, nonbiological siblings, and singletons.
- Employed statistical modeling to assess genetic and environmental variances.
Main Results:
- Nonshared environmental influences were predominant across studied problem behaviors.
- Substantial genetic influences were found for externalizing behaviors, but not internalizing behaviors.
- Findings for total problem score, attention problems, and externalizing behaviors aligned with twin studies, but internalizing behaviors did not.
- Variances in total problem score, externalizing, delinquent, and aggressive behaviors were smaller in singletons than siblings, attributed to sibship size factors.
- Significant sex differences were observed, with larger variances in boys for externalizing and aggressive behaviors, potentially due to genetic factors.
Conclusions:
- Nonshared environment plays a key role in child problem behaviors among international adoptees.
- Genetic influences are specific to externalizing behaviors, unlike internalizing behaviors.
- Sibling interactions and sibship size may influence behavioral variance.
- Sex-specific genetic influences may contribute to externalizing behaviors in boys.
Abstract:
Genetic and environmental influences on problem behaviors were studied in a sample of international adoptees. Parental ratings of childrens' problem behaviors were obtained with the Child Behavior Checklist (CBCL). The sample (mean age, 12.4 years) comprised a group of biological siblings (111 pairs), a group of nonbiological siblings (221 pairs), and a group of singletons (94). Nonshared environmental influences were most important for problem behaviors studied in this paper. Genetic influences were substantial for Externalizing behaviors but unimportant for Internalizing behaviors. For the CBCL total problem score, Attention Problems, and Externalizing behaviors, the results of the present study were in agreement with findings from twin studies. The lack of genetic influences on Internalizing behaviors contrasts with results from twin studies. For the total problem score, the Externalizing grouping, Delinquent Behavior, and Aggressive Behavior, variances for singletons were significantly smaller than for siblings. Model fit indices indicated that these differences in variances are better attributed to smaller effects of factors associated with sibship size than to active influences of siblings on each other. Significant sex differences were found for 8 of the 10 scales. The larger variances for boys on the Externalizing grouping and Aggressive Behavior could be explained by genetic influences.