Parenting, Attachment Security and Adjustment Outcomes: The Role of Nonshared Environment

A great deal of research has focussed on uncovering the antecedents of human behaviour. Studies have implicated parenting as having a fundamental impact on the developmental trajectories of children from the moment they are born, through infancy, adolescence, and their journey to adulthood. This thesis will explore the relationship between parenting and outcomes for children through to adolescence. Part one is a review of the literature examining the evidence for the association between differential parenting and differential adjustment outcomes in externalizing behaviour, internalizing behaviour, temperament, social, and cognitive domains. The review addresses the key question, ‘is differential parenting associated with differential outcomes for children growing up in the same family?’. Part two of the thesis presents the empirical paper for a cross-sectional study observing the association between relative differences in parenting and relative differences in attachment security in a sample of monozygotic twins. The study used a monozygotic twin difference design to also examine differences in parenting and differences in adjustment outcomes in the sample, as well as differences in attachment security and adjustment outcomes. Part three is a critical appraisal of the research, reflecting on the process of the preparation, formation and conducting of the study. The impact of the design and methods on the findings are considered, as well as the researchers’ subjectivity.