Family relationships and children's emotional adjustment as correlates of maternal and paternal differential treatment: a replication with toddler and preschool siblings.

Recent behavioral genetic research emphasizes the nonshared family environment as an important contributor to psychological differences between siblings raised in the same family. Most studies of nonshared sibling experiences have examined the effects of differential maternal and paternal treatment separately and have not examined family-level processes. This study attempted to replicate the findings of McHale, Crouter, McGuire, and Updegraff and also of Volling in which relations between family patterns of differential parental treatment, child outcomes, and family functioning were examined. Questionnaire data were collected from 60 maritally intact families with toddler and preschool siblings. Congruence in mothers' and fathers' reports of differential treatment (i.e., similar treatment from both mother and father) was most frequent. Parents' reports of differential enjoyment were related to differential favoritism, whereas their reports of differential discipline were not. Both mothers and fathers were more likely to discipline the older sibling than the younger toddler. Sibling and marital harmony characterized families in which the father disciplined the older sibling more and mothers disciplined the two children equally. Incongruent patterns of differential favoritism (i.e., one parent treats the children equally while the other favors one child) were associated with marital distress. Preschool siblings exhibited greater internalizing and externalizing symptoms when both mothers and fathers disciplined them more than their younger sibling. The findings of this study with very young siblings differ in some respects from those with older children and suggest that future research needs to examine differential parental treatment as a developmental process across childhood.