This paper follows earlier research (Rowe et al., 1992) in evaluating the b
asis of family influences on adolescent delinquent behavior. Delinquency is
measured in a number of different ways to account for important theoretica
l distinctions that exist in the delinquency literature. We use recently id
entified kinship structure in a large national data set - the National Long
itudinal Survey of Youth - to estimate genetic and shared environmental inf
luences on self-reported delinquency scores. Our analytic model is based on
DF analysis, a regression procedure used to estimate parameters reflecting
genetic and environmental influence. Results suggest a consistent and mode
rate genetic basis to sibling similarity in delinquency and little evidence
of a shared environmental basis. A large amount of variance is attributabl
e to nonshared influences and/or measurement error. Our findings suggest th
at the search for environmental influences on adolescent delinquency should
focus on those that are not shared by siblings.