Sibling Interaction
and Behavior Study (SIBS) and Research on Adoption
To better get a handle
on the nature of environmental influence, Bill
Iacono and I started the Sibling Interaction and Behavior Study (SIBS)
in 1999. SIBS is a study of 400 adoptive and 200 non-adoptive families, each
consisting of a pair of adolescent siblings and their parents. A major aim
of SIBS is to determine whether the behavior and attitudes of an older sibling
represent a major source of environmental influence on adolescent substance
use and abuse. The rationale for this study draws from some of our earlier
work with adoptive families. In that work we showed that, once genetic factors
were controlled, parents appeared to have little influence on adolescent substance
use (McGue et al., 1996a
and 1996b). In contrast sibling
effects appeared to be strong.
A second question we
are exploring in SIBS concerns the psychological adjustmenmt of adopted youth.
In our earlier research (Sharma et al. 1996a and 1996b), we showed that adopted
individuals placed as infants show little psychological differences from nonadopted
individuals. In SIBS we hope to extend these findings using a methodlogically
stronger research design.