Parental tradition transfer to children is pivotal for their socialization, identity formation, and culture perpetuation. But what motivates parents to transfer traditions to their children? We hypothesized that nostalgia, an emotion strengthening interpersonal bonds, would promote tradition transfer through parent-child relationship closeness. We tested these hypotheses using cross-sectional (Studies 1 and 4), cross-lagged (Study 2 and preregistered Study 5), and experimental (Studies 3 and 6) designs. In Studies 1 to 3, nostalgia was associated with, had lagged effect on, and promoted tradition transfer. In Studies 4–6, parent-child relationship closeness mediated the link between nostalgia and tradition transfer. The findings enrich our understanding of the vertical transmission of knowledge, customs, and values, offering insight into how intergenerational bonds are reinforced and cultural heritage is maintained.