Understanding and Preventing Violence, Volume 2: Biobehavioral Influences (1994)
Chapter: NORWEGIAN TWIN STUDY
ADULT ANTISOCIAL BEHAVIOR
The bulk of the literature relevant to genetics and violence comprises studies of adult criminality. The results from early twin studies are summarized in Table 4. Compared to the concordances for juvenile delinquency (see Table 3), there appears stronger evidence for the role of genes in adult antisocial behavior than in adolescent delinquency. Although the methodology of most of these twin studies is poor by absolute standards, they are largely the same studies that generated the juvenile data. Strong methodological biases might be expected to affect both the younger and the older twins in a single series, yet the concordance rates appear to differ.
The more modern studies have undergone recent review by Rowe and Osgood (1984), Ellis (1982), and Walters and White (1989). Here, the samples are reviewed and described with an eye on the generalizability of the results.
NORWEGIAN TWIN STUDY
Dalgard and Kringlen (1976) identified male twins born in Norway between 1921 and 1930, of whom at least one member had appeared in a national police register by the end of 1966. The 139 intact and located pairs were interviewed personally, or information was gathered through family history interviews with relatives. Like other selected samples, the registered probands were
TABLE 4 Pooled Twin Concordance Rates for Adult Criminality in Identical and Same-Sex Fraternal Twins (early studies)a
