Table 1.
Measures of aggression collected across the four samples
| Sample | Age | Measures | Informant |
|---|---|---|---|
| Twins Early Development Study (TEDS) | 9 | Strengths and Difficulties Questionnaire (SDQ, Goodman, 1997); | Parent reports |
| Reactive and Proactive Aggression Questionnaire (RPAQ, Dodge and Coie, 1987) | |||
| 12 | SDQ | Parent reports | |
| 16 | SDQ; Self-Report Delinquency Scale (Elliott et al., 1985) | Self-reports | |
| Netherlands Twins Register (NTR) | 10 | Child Behaviour Check List (CBCL; Achenbach and Edelbrock, 1991) | Parent report |
| 12 | CBCL | Parent report | |
| 14 | Youth Self Report (YSR, Achenbach et al., 1995; Wesseldijk et al., 2017) | Self-reports | |
| 16 | YSR | Self-reports | |
| FinnTwin12 (FT12) | 12 | Multidimensional Peer Nomination Inventory (MPNI, Pulkkinen et al., 1999) | Parent reports |
| 14 | MPNI | Self-reports | |
| 17 | MPNI | Self-reports | |
| Childhood and Adolescent Twin Study of Sweden (CATSS) | 9 | Autism – Tics, ADHD and other Comorbidities (A-TAC; Hansson et al., 2005) | Parent reports |
| 15 | RPAQ; SDQ; and Self-Reported Delinquency questionnaire (SRD; Junger-Tas et al., 1994) | Self-reports | |
| 18 | SRD; and Life History of Aggression scale (LHA, Coccaro et al., 1997) | Self-reports |