title: A twin study of attachment in preschool children.
abstract: The degree to which individual differences in child-parent attachment were mediated by genetic, shared environmental, and nonshared environmental influences was investigated. One hundred and ten preschool-aged twin pairs (N = 220) were assessed in the Strange Situation and coded using conventional four-way classifications and a continuous measure of attachment security. The degree of sibling similarity in attachment was substantial, with an overall concordance rate of 67% at the secure/insecure level. The degree of concordance was equally high in monozygotic and dizygotic twin pairs, 70% and 64%, respectively, suggesting little genetic influence but a moderate degree of discordance. Twin similarity on the continuous measure of attachment security was r(57) = .48 and r(53) = .38 for monozygotic and dizygotic twin pairs, respectively, also consistent with a modest role for genetic influence but a significant effect for shared and nonshared environment. The implications for genetic influences on the environment and for understanding nonshared and shared environmental influences are discussed.
authors.affiliation: Department of Psychology, Institute of Psychiatry, London, UK. spjwtoc@iop.kcl.ac.uk
authors.forename: T G
authors.initials: TG
authors.lastname: O'Connor
authors.forename: C M
authors.initials: CM
authors.lastname: Croft
mesh_terms: D000328:Adult; D002675:Child, Preschool; D005260:Female; D005824:Genetics, Behavioral; D006801:Humans; D007206:Individuality; D008297:Male; D008960:Models, Psychological; D009679:Nuclear Family / Q000523:psychology*; D009769:Object Attachment; D010287:Parent-Child Relations; D013694:Temperament; D014427:Twins / Q000523:psychology*; D014429:Twins, Dizygotic / Q000523:psychology; D014430:Twins, Monozygotic / Q000523:psychology