title: Genetic, environmental and gender influences on attachment disorder behaviours.
abstract: BACKGROUND
  Despite current interest in attachment disorder, there is concern about its discrimination from other disorders and an unproven assumption of an environmental aetiology.
  
  
  OBJECTIVE
  To test whether behaviours suggestive of attachment disorder are distinct from other childhood behavioural and emotional problems and are solely environmentally determined.
  
  
  METHODS
  In a community sample of 13,472 twins, we carried out factor analysis of questionnaire items encompassing behaviours indicative of attachment disorder, conduct problems, hyperactivity and emotional difficulties. We used behavioural genetic model-fitting analysis to explore the contribution of genes and environment.
  
  
  RESULTS
  Factor analysis showed clear discrimination between behaviours suggestive of attachment disorder, conduct problems, hyperactivity and emotional problems. Behavioural genetics analysis suggested a strong genetic influence to attachment disorder behaviour, with males showing higher heritability.
  
  
  CONCLUSIONS
  Behaviours suggestive of attachment disorder can be differentiated from common childhood emotional and behavioural problems and appear to be strongly genetically influenced, particularly in boys.
authors.affiliation: Section of Psychological Medicine, University of Glasgow, Glasgow, UK. h.minnis@clinmed.gla.ac.uk
authors.forename: Helen
authors.initials: H
authors.lastname: Minnis
authors.forename: Joanne
authors.initials: J
authors.lastname: Reekie
authors.forename: David
authors.initials: D
authors.lastname: Young
authors.forename: Tom
authors.initials: T
authors.lastname: O'Connor
authors.forename: Angelica
authors.initials: A
authors.lastname: Ronald
authors.forename: Alison
authors.initials: A
authors.lastname: Gray
authors.forename: Robert
authors.initials: R
authors.lastname: Plomin
mesh_terms: D002648:Child; D005163:Factor Analysis, Statistical; D005260:Female; D005824:Genetics, Behavioral; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D010553:Personality Development; D019962:Reactive Attachment Disorder / Q000235:genetics*; D012931:Social Environment; D014427:Twins