Long-term legacy of parents' secure base script knowledge: Cascading implications for family relationships and children's positive development.

A large body of research implicates adults' attachment security, largely formed in their early experiences, as a key factor shaping their future romantic and parenting relationships. Family system theories suggest that the interparental relationship is key for other relationships within the family, including those in individual mother- and father-child dyads. Few studies, however, have elucidated how the legacy of parents' attachment security unfolds through family relationships to child outcomes. We test a developmental longitudinal cascade, conceptualized as a sequential mediation model, from parents' attachment security, assessed as their secure base script knowledge when children were infants, to their self-reported interparental relationship quality at toddler age, to their observed relationships with their children at age 3 years, and, ultimately, to children's developmental outcomes at age 4.5 years (self-regulation and moral self). We leverage multimethod data (interviews, reports, observations) from a study of 200 community families in the U.S. Midwest (mothers, fathers, and children). We adopt recent perspectives that emphasize positive socialization processes and successful outcomes rather than detrimental pathways conferring risks. In analyses that controlled for the continuity of interparental and parent-child relationships, we supported several mediational paths. Results for mother-child dyads supported the entire hypothesized longitudinal sequence from mothers' attachment security to the mother-child relationship to children's positive developmental outcomes. For father-child dyads, that key cascade was not supported. However, several shorter alternative indirect paths were found in both dyads. (PsycInfo Database Record (c) 2026 APA, all rights reserved).