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A Twin Study of Attachment Style in Young Adults


  • The first author wishes to dedicate this article to the memory of his beloved mother, Anna Imbò, PsyD, who taught him the meaning of attachment and love, and sadly passed away during the completion of this work.
    Also the authors thank Guido Alessandri, PhD, for his kind and helpful assistance with the statistical analysis.

concerning this article should be addressed to Angelo Picardi, Mental Health Unit, Center of Epidemiology, Surveillance and Health Promotion, Italian National Institute of Health, Viale Regina Elena 299, 00161 Rome, Italy. Email:


ABSTRACT The relative contribution of genetic and environmental influences to individual differences in attachment security is still incompletely understood. We assessed attachment style with the Experiences in Close Relationships questionnaire in a volunteer sample of 677 twins (43% male) ages 23–24 years drawn from the population-based Italian Twin Register, who belonged to 244 complete pairs (46% monozygotic) and 189 unmatched pairs. Genetic structural equation modeling was performed with the Mx program. Genetic effects accounted for 45% and 36% of individual differences in attachment-related anxiety and avoidance, respectively. Furthermore, the covariation between anxiety and avoidance was found to be mainly due to genetic factors, with heritability of the latent attachment security phenotype estimated at 62%. Unshared environmental factors explained the remaining proportion of variance. Although our findings are best regarded as preliminary given some study limitations, they suggest that both nature and nurture contribute to individual differences in adult attachment.

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