title: Do twins differ from single-born children on rates of behavioral difficulty in early childhood? A study of sibling relationship risk factors.
abstract: The hypothesis that twinning raises risk for behavioral difficulties in childhood is persistent, yet there is limited and inconsistent empirical evidence. Simple mean comparison without control for confounders provides data on prevalence rates but cannot provide knowledge about risk or etiology. To assess the effect of twin relationship on behavior, comparison of patterns of association with single-born siblings may be informative. Analyses of data from an Australian sample of twins and single-born children (N = 305, mean age 4 years 9 months, and a follow-up 12 months later) were undertaken. The outcome measure was the Strengths and Difficulties Questionnaire. Predictor and control measures were obtained from parent report on the sibling/co-twin relationship behavior, family demographics, and obstetric history. We assessed difference between twins and single-born children in two respects: (a) mean behavioral difficulties, and (b) patterns of association between sibling relationship and behavioral difficulties, controlling for confounders. Results showed no differences in mean levels of behavioral difficulties between twins and single-born siblings identifying the importance of statistical control for family and obstetric adversity. Differences in patterns of association were found; for twin children, conflict in their co-twin relationship predicted externalizing behaviors, while for single-born children conflict predicted internalizing behaviors. The findings of mean differences between twin and single-born children in social background, but not in behavioral difficulties, underscore the necessity of statistical control to identify risk associated with twinning compared with risk associated with family and obstetric background factors.
authors.affiliation: Department of Psychology,University of Oslo,Oslo,Norway.
authors.forename: Mona
authors.initials: M
authors.lastname: Bekkhus
authors.affiliation: School of Psychology and Counselling,Queensland University of Technology,Brisbane,Australia.
authors.forename: Sally
authors.initials: S
authors.lastname: Staton
authors.affiliation: Department of Psychology,University of Oslo,Oslo,Norway.
authors.forename: Anne I H
authors.initials: AI
authors.lastname: Borge
authors.affiliation: School of Psychology and Counselling,Queensland University of Technology,Brisbane,Australia.
authors.forename: Karen
authors.initials: K
authors.lastname: Thorpe
mesh_terms: D001315:Australia; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D011897:Random Allocation; D012307:Risk Factors; D012801:Sibling Relations; D011795:Surveys and Questionnaires; D014427:Twins / Q000523:psychology*