The likely generalisability of our results is indicated by our replication of several well established findings. For example, depression and anxiety were both more common in girls than boys, a finding that has been reported several times previously (e.g. Costello et al. 2005; Hankin et al. 1998). As has been found elsewhere (e.g. Tremblay 2010) delinquency was found to increase with age, whereas physical aggression and oppositionality decreased. Correlations between behavioural phenotypes were as would be expected, with higher correlations within the externalising (oppositionality, delinquency, physical aggression) and internalising (depression and anxiety) categories than between them.
