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Nonshared Environmental Influences on Individual Differences in Early Behavioral Development: A Monozygotic Twin Differences Study
Author(s) -
Asbury Kathryn,
Dunn Judith F.,
Pike Alison,
Plomin Robert
Publication year - 2003
Publication title -
child development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.103
H-Index - 257
eISSN - 1467-8624
pISSN - 0009-3920
DOI - 10.1111/1467-8624.00577
Subject(s) - psychology , prosocial behavior , developmental psychology , twin study , monozygotic twin , behavioural genetics , anxiety , socioeconomic status , gene–environment interaction , conduct disorder , demography , heritability , population , genetics , psychiatry , sociology , biology , biochemistry , chemistry , gene , genotype
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.