title: The importance of shared environment in mother-infant attachment security: a behavioral genetic study.
abstract: In a sample of 157 monozygotic and dizygotic twins, genetic and environmental influences on infant attachment and temperament were quantified. Only unique environmental or error components could explain the variance in disorganized versus organized attachment as assessed in the Ainsworth Strange Situation Procedure. For secure versus nonsecure attachment, 52% of the variance in attachment security was explained by shared environment, and 48% of the variance was explained by unique environmental factors and measurement error. The role of genetic factors in attachment disorganization and attachment security was negligible. Genetic factors explained 77% of the variance in temperamental reactivity, and unique environmental factors and measurement error explained 23%. Differences in temperamental reactivity were not associated with attachment concordance.
authors.affiliation: Center for Child and Family Studies, Leiden University, The Netherlands.
authors.forename: Caroline L
authors.initials: CL
authors.lastname: Bokhorst
authors.forename: Marian J
authors.initials: MJ
authors.lastname: Bakermans-Kranenburg
authors.forename: R M Pasco
authors.initials: RM
authors.lastname: Fearon
authors.forename: Marinus H
authors.initials: MH
authors.lastname: van IJzendoorn
authors.forename: Peter
authors.initials: P
authors.lastname: Fonagy
authors.forename: Carlo
authors.initials: C
authors.lastname: Schuengel
mesh_terms: D005260:Female; D005824:Genetics, Behavioral; D006801:Humans; D007206:Individuality; D007223:Infant; D008131:London; D008297:Male; D009034:Mother-Child Relations; D009426:Netherlands; D009769:Object Attachment; D016487:Parenting / Q000523:psychology; D010552:Personality Assessment / Q000706:statistics & numerical data; D011594:Psychometrics; D012307:Risk Factors; D012931:Social Environment; D013694:Temperament; D014427:Twins / Q000235:genetics / Q000523:psychology*