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

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.

Body Size of Twins Compared with Siblings and the General Population: From Birth to Late Adolescence

“…30 We were particularly interested whether there would also be a difference in BMI between adolescent twins and siblings. Indeed, siblings had a higher BMI than twins in the questionnaire sample, but in contrast to the test protocol sample, siblings were slightly taller than twins.…”

Genetic Influences on Thought Problems in 7-Year-Olds: A Twin-Study of Genetic, Environmental and Rater Effects

“…A number of quantitative genetic studies have examined problem behavior in children with the CBCL, with the main focus on internalizing and externalizing behavior problems (Bartels et al, 2004a;Bartels et al, 2004b;Bartels et al, 2007;Edelbrock et al, 1995;Gjone & Stevenson, 1997;Hudziak et al, 2000;Leve et al, 1998;Schmitz & Mrazek, 2001;Silberg et al, 1994;Van den Oord et al, 1995;Van der Valk et al, 1998;Zahn-Waxler et al, 1996) and a number of these studies have modeled the agreement and disagreements among parental reports. For example, in a study by Rowe and Kandel (1997), parents rated the internalizing and externalizing behavior of their two oldest children (between 9 and 17 years old).…”

“…Hewitt et al, (1992) studied internalizing behavior in prepubertal (8-11 years) and pubertal twins (12-16 years), and found evidence for such genetic effects. Dutch twin studies on internalizing and externalizing behaviors also found that the unique viewpoint of parents does not solely reflect rater bias (Bartels et al, 2003;Bartels et al, 2004a;Bartels et al, 2007;Van der Valk et al, 2001;Van der Valk et al, 2003).…”

The Young Netherlands Twin Register (YNTR): Longitudinal Twin and Family Studies in Over 70,000 Children

“…Importantly, the pattern of non-response did not differ between MZ and dizygotic (DZ) mothers. For internalizing and externalizing problems, Bartels et al (2007) compared the level of problem behaviors in 3-year-old twins between three groups: a group that participated at ages 3, 7, 10, and 12, a group that participated only at age 3, and a group with temporary non-participation. No significant mean differences in externalizing and internalizing behavior problems were found between the three groups.…”

“…They are distinguished by recruitment and ways of data collection. Twins participating in the YNTR are registered at birth by their parents, and are recruited with the help of a commercial baby organization that visits parents of newborns and the 'Dutch association for parents of multiples' (NVOM; Bartels et al, 2007;Boomsma et al, 2002). The data collection for the YNTR and ANTR differs, simply because as long as twins are under age 14 their parents and their teachers are the main informants, whereas at later ages, the data are collected through self-reports.…”