Genetic and environmental contributions to adult attachment styles: Evidence from the Minnesota Twin Registry.

Attachment theory, as originally outlined by Bowlby (1973, 1980, 1969/1982), suggests that the ways people think, feel, and behave in close relationships are shaped by the dynamic interplay between their genes and their social environment. Research on adult attachment, however, has largely focused on the latter, providing only a partial picture of how attachment styles emerge and develop throughout life. The present research leveraged data from the Minnesota Twin Registry, a large sample of older adult twins (N = 1,377 twins; 678 pairs; Mage = 70.40 years, SD = 5.42), to examine the relative contributions of genetic and environmental factors to adult attachment styles. Participants reported on both their general attachment styles and relationship-specific attachments to their mothers, fathers, partners, and best friends. The results suggest that attachment styles are partly heritable (∼36%) and partly attributable to environmental factors that are not shared between twins (∼64%). Heritability estimates were somewhat higher for parent-specific attachment styles (∼51%), whereas nonshared environmental factors accounted for larger proportions of the variance in partner- and best friend-specific attachment styles. Using multivariate biometric models, we also examined the genetic and environmental factors underlying the covariation among people's relationship-specific attachment styles. The findings indicate that the similarities among people's avoidant tendencies in different relationships can be explained by a single, higher order latent factor (e.g., global avoidance). In contrast, the genetic and environmental factors underlying attachment anxiety appear to be more differentiated across specific close relationships. (PsycInfo Database Record (c) 2025 APA, all rights reserved).