A critique of research examining whether early experiences with primary caregivers are reflected in adaptation is that relevant longitudinal studies have generally not employed genetically informed research designs capable of unconfounding shared genes and environments. Using the twin subsample (N = 485 pairs) of the Early Childhood Longitudinal Study-Birth Cohort, the current study provides evidence that early parental support (derived from observations at 24 months and around age 4, in prekindergarten) is associated with academic skills (r = 0.32), social competence (r = 0.15), and externalizing behavior (r = -0.11) in kindergarten. Crucially, the shared environment accounted for virtually all of the correlation between parenting and academic skills, roughly half of the association between parenting and social competence, and approximately one fourth of the correlation between parenting and externalizing behavior.