ABSTRACT
This longitudinal monozygotic (MZ) twin differences study explored associations between birthweight and early family environment and teacher-rated behaviour problems and academic achievement at age 7. MZ differences in anxiety, hyperactivity, conduct problems, peer problems and academic achievement correlated significantly with MZ differences in birthweight and early family environment, showing effect sizes of up to 2%. As predicted by earlier research, associations increased at the extremes of discordance, even in a longitudinal, cross-rater design, with effect sizes reaching as high as 12%. As with previous research some of these non-shared environmental (NSE) relationships appeared to operate partly as a function of SES, family chaos and maternal depression. Higher-risk families generally showed stronger negative associations.
Subject(s)
Birth Weight , Child Behavior Disorders/genetics , Parenting , Anxiety Disorders , Attention Deficit Disorder with Hyperactivity , Child , Child, Preschool , Conduct Disorder , Educational Status , Environment , Female , Humans , Longitudinal Studies , Male , Peer Group , Risk Factors , Students , Twins, MonozygoticABSTRACT
The overarching goal of the study was to identify links between sibling relationship quality in early/middle childhood with children's adjustment, having accounted for the effects of parent-child relationship quality. The sample consisted of 101 working and middle-class 2-parent English families with 2 children ages 4-8 years. Parents provided reports of sibling relationship quality, the parent-child relationship, and the children's prosocial and problematic behaviors. The children also provided reports of their familial relationships with a puppet interview. Results indicated that sibling relationship quality was associated with the older siblings' adjustment, controlling for the children's relationships with parents. In addition, the pattern of findings suggested that positivity within the sibling relationship was more strongly linked with child adjustment than was sibling conflict.
Subject(s)
Adaptation, Psychological/physiology , Child Behavior/psychology , Sibling Relations , Birth Order/psychology , Child , Child, Preschool , Conflict, Psychological , England , Humans , Negativism , Parent-Child Relations , Social Behavior , Surveys and QuestionnairesABSTRACT
The monozygotic (MZ) twin differences method was used to investigate nonshared environmental (NSE) influences independent of genetics. Four-year-old MZ twin pairs (N = 2,353) were assessed by their parents on 2 parenting measures (harsh parental discipline and negative parental feelings) and 4 behavioral measures (anxiety, prosocial behavior, hyperactivity, and conduct problems). Within-pair differences in parenting correlated significantly with MZ differences in behavior, with an average effect size of 3%. For the extreme 10% of the parenting-discordant and behavior-discordant distributions, the average NSE effect size was substantially greater (11%), suggesting a stronger NSE relationship for more discordant twins. NSE relationships were also stronger in higher risk environments, that is, families with lower socioeconomic status, greater family chaos, or greater maternal depression.