Sibling Influences, Sibling Similarities, and Parent Care in Late Life.

Researchers have extensively examined why some particular adult children provide care to their aged parents, but rarely considered sibling similarities and influences in their examinations. Guided by social learning theory and diffusion of responsibility theory, we investigate whether sibling similarities are associated with adult children's care hours, net of the parent's and child's characteristics. Based on social comparison theory, we further examine whether such associations differ across adult children, depending on whether adult children share the same characteristics as their siblings. Using Round 5 data from the National Health and Aging Trends Study, we find that adult children provide more care hours when siblings are close in age, supporting social learning theory. In contrast, adult children provide fewer care hours in the presence of a greater share of siblings who are unpartnered or close to the parents, supporting diffusion of responsibility theory. Consistent with social comparison theory, social learning is stronger for younger adult children, and diffusion of responsibility is weaker when adult children are unpartnered or close to the parents. Findings from this study highlight the importance for future research of going beyond parent-child dyads and incorporate sibling influences when studying the caregiving behavior of adult children.