354 qAmerican Association on Mental Retardation Life Course Studies of Siblings of Individuals With Developmental Disabilities

The sibling relationship constitutes the longest lasting family tie, beginning with the birth of the younger sibling and ending with the death of one member of the sibling pair. Siblings share a com-mon family heritage, both genetically and experi-entially, and perhaps for this reason, the sibling re-lationship is normatively characterized as egalitari-an, reciprocal, and mutual. How is the sibling re-lationship distinct when one member of the sibling pair has a developmental disability? Aspects of the sibling tie might be atypical in this context, in sev-eral respects. For example, the duration of the re-lationship might be shorter, as some individuals with developmental disabilities have a more limited life-span. In addition, there may be less genetic an