neighborhoods there was greater evidence of genetic influence.89 Conversely, in more supervised and restricted environments, there was less opportunity to express genetic predispositions and greater influence of environmental effects.89,90 These analyses suggest that less restrictive environments provide greater opportunities for the expression of genetic predispositions, although again it appears that these effects may be age specific: the findings described above were reported for a sample of 16-18 year olds but using a very similar approach these authors were unable to replicate findings of significant moderation of genetic effects by socioregional factors in a younger sample of 12 to 14 year old Finnish twins.91 Likewise, low levels of parental monitoring92 as well as increased affiliations with substance using peers,93 have been found to augment the importance of genetic influences of substance use.
