Previous studies have reported significant heritabilities for aggressive
behavior in children and adolescents. Most of these studies have used
data from only one source, such as ratings by parents. Because questions
have been raised about potential biases in data obtained from parents
and other kinds of informants, a team of researchers at the Institute
of Psychiatry in London evaluated the contributions of four sources
of data to tests of genetic effects on young children's antisocial behavior
(Arsenault et al., 2003). The children were 2,232 5-year-old British
twins who were participating in the Environmental Risk (E-risk) Longitudinal
Twin Study. The assessment data included mothers' CBCL ratings, teachers'
TRF ratings, ratings by examiners who observed the children in standardized
situations, and children's self-reports obtained in puppet interviews
where each child identified puppets whose behavior was most like the
child's own behavior. Correlations between scores obtained from the
different informants (mothers, teachers, observers, children) were similar
to the low correlations found between these combinations of informants
in meta-analyses of many studies. However, complex statistical analyses
indicated that antisocial behavior agreed upon by all types of informants
(i.e., antisocial behavior that was observed in multiple contexts) was
highly heritable, yielding a heritability estimate of 82%. Furthermore,
the low correlations among scores from different informants did not
result from biases in the informants' ratings. Instead, the variations
in antisocial behavior that were specific to reports by each type of
informant were influenced by genetic factors. In other words, the low
correlations between informants' reports resulted from the fact that
each type of informant validly captured different, genetically influenced
aspects of children's antisocial behavior. These different aspects of
antisocial behavior that were detected by each type of informant were
thus in addition to the genetically influenced aspects of antisocial
behavior that were consistent across multiple informants and the contexts
to which their ratings referred. Arsenault et al. concluded that "researchers
studying children's behavior disorders should try to collect data from
different sources," and that "using all the information from
each rater to create composite scores will capture more meaningful variation
than restricting composites to only the information agreed upon by all
raters" (p. 844).
Reference:
Arsenault, L., Moffitt, T.E., Caspi, A., Taylor, A., Rijsdijk, F.V.,
Jaffee, S.R., Ablow, J.C, & Measelle, J.R. (2003). Strong genetic
effects on cross-situational antisocial behaviour among 5-year-old children
according to mothers, teachers, examiner-observers, and twins' self-reports.
Journal of Child Psychology and Psychiatry, 44, 832-848.