Genetic and environmental influences on a measure of infant attachment security.
A twin study of infant attachment security at age 24 months was conducted on archival data for a sample of 99 MZ pairs and 108 DZ pairs from the Louisville Twin Study. MZ concordance for attachment was 62.6%, which was significantly greater than the DZ concordance of 44.4%. Concordances were transformed into polychoric correlations, and LISREL was used to conduct a quantitative genetic analysis of the data. Results indicated that 25% of the variability in attachment was attributable to genetic factors, and the remaining 75% was attributable to non-shared environmental effects. No evidence was found for a contribution from shared environmental influences to attachment security. Possible concerns about the validity of twin methodology are addressed and various interpretations of the results are presented.
Finkel
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Indiana University Southeast, New Albany 47150, USA. dfinkel@ius.edu
Matheny
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AP
D001010:Anxiety, Separation / Q000235:genetics / Q000523:psychology; D002675:Child, Preschool; D004777:Environment; D005260:Female; D006801:Humans; D007629:Kentucky; D016018:Least-Squares Analysis; D008137:Longitudinal Studies; D008297:Male; D008425:Maternal Behavior; D008957:Models, Genetic; D009034:Mother-Child Relations; D009769:Object Attachment; D002666:Psychology, Child; D012107:Research Design; D013694:Temperament; D014429:Twins, Dizygotic / Q000235:genetics* / Q000523:psychology*; D014430:Twins, Monozygotic / Q000235:genetics* / Q000523:psychology*; D014743:Videotape Recording