Gender differences and developmental change in externalizing disorders from late adolescence to early adulthood: A longitudinal twin study.
Level 3 - non-randomized controlled study
Non-randomized longitudinal twin cohort study
PubMed 17696699 · doi:10.1037/0021-843X.116.3.433
What was done
Data from over 1,000 male and female twins in the Minnesota Twin Family Study were analyzed from age 17 to age 24. Researchers evaluated developmental changes, gender differences, and biometric (genetic and environmental) contributions to symptom levels across four externalizing disorders: adult antisocial behavior, alcohol dependence, nicotine dependence, and drug dependence.
What was found
Symptoms across all four externalizing disorders increased from age 17 to 24 in both men and women, with men increasing at a greater rate and widening the gender gap over time. A latent Externalizing factor accounted for these mean-level gender differences across specific disorders. Biometric modeling showed increasing genetic variation and heritability across adulthood for men, but decreasing genetic variation and increasing environmental influences for women. The abstract does not report specific numerical estimates, effect sizes, or confidence intervals.
Why it matters
This study shows that the divergence in externalizing psychopathology between young men and women reflects differing biometric pathways, with genetic influences strengthening in males while environmental factors become more dominant in females.
Limits
The abstract omits exact sample sizes beyond the general '>1,000' figure, and provides no exact statistical metrics or confidence intervals. Findings from a single regional twin registry may have limited generalizability to other populations.
Cited by
- supports Twin, adoption, and direct DNA studies indicate that the underlying genetic liability toward disinhibition and self-regulation problems is consistent across men and women, differing in mean behavior rates rather than genetic etiology.