Twin Research and Human Genetics

Articles

Young Netherlands Twin Register (Y-NTR): A Longitudinal Multiple Informant Study of Problem Behavior

Meike Bartelsa1 c1, C. E. M. (Toos) van Beijsterveldta2, Eske M. Derksa3, Therese M. Stroeta4, Tinca J. C. Poldermana5, James J. Hudziaka6 and Dorret I. Boomsmaa7

a1 Department of Biological Psychology, Vrije Univerisiteit, Amsterdam, the Netherlands. m.bartels@psy.vu.nl

a2 Department of Biological Psychology, Vrije Univerisiteit, Amsterdam, the Netherlands.

a3 Department of Biological Psychology, Vrije Univerisiteit, Amsterdam, the Netherlands.

a4 Department of Biological Psychology, Vrije Univerisiteit, Amsterdam, the Netherlands.

a5 Department of Biological Psychology, Vrije Univerisiteit, Amsterdam, the Netherlands.

a6 Departments of Psychiatry and Medicine (Division of Human Genetics), Center for Children, Youth and Families, University of Vermont, College of Medicine Burlington, Burlington, Vermont, United States of America.

a7 Department of Biological Psychology, Vrije Univerisiteit, Amsterdam, the Netherlands.

Abstract

The Netherlands Twin Register (NTR) was established around 1987 at the Vrije Universiteit in Amsterdam, the Netherlands. The current article summarizes the longitudinal genetic analyses of maternal and paternal ratings of twins' behavior as a function of the sex of the children for the traits of aggression (AGG), attention problems (AP), anxious/depression (ANX), internalizing behavior (INT) and externalizing behavior (EXT). We found that genetic influences are the most important factor in explaining individual differences in these traits. For most phenotypes, influences of genetic factors fluctuate throughout development, with the exception of AP, for which genetic influences remain of similar magnitude. Changes in genetic influences parallel those in shared environmental influences, while nonshared environmental influences remain relatively constant. Around 10% to 20% of the variance is accounted for by parent-specific shared environment, which includes rater bias. For all phenotypes, stability throughout childhood is accounted for by genetic and shared environmental factors, while nonshared environmental influences are mainly age/measurement specific. About 15% of the phenotypic stability is accounted for by rater-specific shared environmental influences, which include rater bias. In conclusion, between ages 3 and 12 genetic factors are the most important cause of individual differences in emotional and behavioral problems.

(Received May 26 2006)

(Accepted July 02 2006)

Correspondence:

c1 Address for correspondence: Meike Bartels, Department of Biological Psychology, Room 2B-47, Vrije Universiteit, Van der Boechorststraat 1, 1081 BT Amsterdam, the Netherlands.

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