Although prior research has detected a step-gap in intergenerational relationships in various aspects, there is a lack of studies examining adult children’s support toward their biological parents and stepparents. We investigated (i) whether adult children provide more support to their biological parents than stepparents; and (ii) whether the childhood co-residence duration is associated with the support given to stepparents.

The data was drawn from the German Family Panel (pairfam). Upward support was indicated by using three different measures, namely, financial, practical, and emotional support provided by adult children to their biological parents and stepparents. A path analysis was conducted to detect the potential differences regarding upward support.

More support was channeled toward the biological parents than the stepparents. Moreover, the length of co-residence during childhood and adolescence was positively associated with the frequency of support provided toward the stepparents. Consequently, an increased childhood co-residence duration decreased the step-gap in upward support, although it did not fully eliminate it.

The findings showed that stepparents are in a more disadvantaged position than the biological parents regarding receiving support from their adult children. In the context of a high old-age dependency ratio, it is important to recognize that stepparents may not have the opportunity to receive adequate support from their families as compared to individuals with biological children.