Do twins differ from single-born XXXX on rates of behavioral difficulty in early childhood? A study of sibling relationship risk factors.

@entity1 @entity146
The hypothesis that twinning raises risk for @entity146 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 @entity1 (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 @entity1 in two respects: (a) mean @entity146 , and (b) patterns of association between sibling relationship and @entity146 , controlling for confounders. Results showed no differences in mean levels of @entity146 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 @entity1 , conflict in their co-twin relationship predicted externalizing behaviors, while for single-born @entity1 conflict predicted internalizing behaviors. The findings of mean differences between twin and single-born @entity1 in social background, but not in @entity146 , underscore the necessity of statistical control to identify risk associated with twinning compared with risk associated with family and obstetric background factors.
