Marrying into it: Siblings-in-law in the social support networks of adults with intellectual and developmental disabilities.

Background: Although attention has been devoted to social supports provided by parents and siblings of adults with intellectual and developmental disabilities (IDD), much less is known about supports provided by the spouses of these siblings-the so-called siblings-in-law. This study examined the role of the sibling-in-law in the social support networks of their brother/sister-in-law with IDD and factors associated with providing greater amounts of tangible, informational and emotional support.

Method: Siblings-in-law of adults with IDD living predominately in the United States (N = 99) participated in a cross-sectional survey. Measures covered demographic and family background, perspectives towards having a brother/sister-in-law with IDD, supports provided and characteristics of the adult with IDD's social support network.

Results: Most siblings-in-law reported providing support to their brother/sister-in-law with IDD. Percentages of siblings-in-law providing support were similar to that of the spouse and the spouse's family in the area of emotional support and similar to percentages of paid professionals in tangible and informational supports. Across all three support types, the main predictor of increased sibling-in-law support levels was a decreased ability of the parents-in-law to care for their child with IDD. Other predictors (e.g. distance from brother/sister-in-law with IDD and disability 'insider' status) varied by support type.

Conclusions: Findings highlight the role of siblings-in-law in the social support networks of adults with IDD, with implications for policy and practice.