title: Adoptee overrepresentation among clinic-referred boys with gender identity disorder.
abstract: OBJECTIVE
  To test the hypothesis that adoptees are overrepresented among a sample of clinic-referred boys with gender identity problems (N = 238). To compare the adoptees and nonadoptees on demographic, behaviour problem, and gender-typed measures.
  
  
  METHODS
  The percentage of clinic-referred boys with gender identity problems adopted in the first 2 years of life ("early adoptees") was compared to the base rate of boys adopted in Ontario. Parent-report and behavioural measures were used to compare the early adoptees with "late adoptees" (adopted after the second year of life) and nonadoptees.
  
  
  RESULTS
  The percentage of boys with gender identity problems who were early adoptees (7.6%) was significantly higher than the base rate of males adopted in Ontario in the first 2 years of life (1.5%). Both the early and late adoptees were significantly less intelligent than the nonadoptees. The early adoptees also had significantly higher externalizing T scores on the Child Behavior Checklist than did the late adoptees and the nonadoptees. The 3 groups did not differ in the percentage who met the complete Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria for gender identity disorder and on 4 other measures of gender-typed behaviour.
  
  
  CONCLUSIONS
  Adoptees are overrepresented among clinic-referred boys with gender identity problems. The reasons for this finding are not clear but may be accounted for by general risk factors that increase the likelihood of clinical referral or by psychosocial and biological factors associated with adoption.
authors.affiliation: Child and Adolescent Gender Identity Clinic, Clarke Institute of Psychiatry, Toronto, Ontario. ZUCKERK@cs.clarke-inst.on.ca
authors.forename: K J
authors.initials: KJ
authors.lastname: Zucker
authors.forename: S J
authors.initials: SJ
authors.lastname: Bradley
mesh_terms: D000300:Adoption / Q000523:psychology*; D000367:Age Factors; D002648:Child; D002653:Child Behavior Disorders / Q000453:epidemiology / Q000523:psychology; D002675:Child, Preschool; D005783:Gender Identity; D006801:Humans; D007223:Infant; D008297:Male; D009864:Ontario / Q000453:epidemiology; D010552:Personality Assessment; D011569:Psychiatric Status Rating Scales; D012017:Referral and Consultation / Q000706:statistics & numerical data; D012307:Risk Factors