This analysis uses linked sibling data from the 1979 National Longitudinal Survey of Youth (NLSY79) to investigate the presence of a relationship between young adult and elderly coresidence within families. I find that children who departed late or returned to the parental home are more likely to have coresident parents later in life, such that even within a given family, parents requiring coresidence live with the child who exited later or returned. I present both linear and non-parametric models of this effect, and contextualize it with a mixed motivation behavioral model of intra-family generosity, which supports preferences consistent with these new facts. I show that neither altruism nor exchange alone can explain the intergenerational link in coresidence. The preferred model suggests that an increase in public aid to emerging young adults may decrease intra-family assistance to elderly individuals due to reduced signaling capacity, an important implication amid current policy discussions.