Genetic, cognitive and intervention effects on parenting, child attachment and children’s psychobiology
Authors:   , Runze Jana 
Published: February 2024

Parents, and their behavior towards their children play a major role in a child’s development. The development of children does not only hold significance for children themselves, but also for society since children grow up to be active members of our society. Problems in the psychobiological development of children have been linked to (mental) health difficulties later in life and subsequent personal, social and economic costs. Preventing the onset of (mental) health difficulties by supporting adaptive child development is therefore highly desired.

Within the broad context of parenting, the main questions of this thesis were what the (genetic) determinants of parental reports and behavior are and in how far parents and genes are determinants of children’s attachment and psychobiology. These questions were answered using two studies: the Leiden Consortium on Individual Development (L-CID) and the Generation R study (GenR).

In Chapter 2, I examined the potential role of genes in response bias of parents and their twin children. Both parents and twins completed a modified Wildman Symptoms Questionnaire and provided salivary DNA samples. From published Genome-Wide Association Studies (GWAS) I derived polygenic score (PGS), which were applied to the GWAS results of our participants’ DNA. Higher polygenic scores for educational attainment and income but not for IQ predicted less acquiescence response bias in parents and children.

In Chapter 3, I investigated whether genetic predispositions to socio-economic and cognitive factors (i.e. educational attainment, IQ and income) can predict sensitive parenting in mothers of the GenR study. Higher maternal PGS of educational attainment (PGS-EA) scores predicted higher observed sensitivity in toddlerhood and early childhood. Child PGS-EA was significantly associated with maternal sensitivity in early childhood, and the effect of maternal PGS-EA was no longer significant when correcting for child PGS-EA. A latent factor of PGSs based on educational attainment, intelligence (IQ), and income showed similar results. Maternal PGSs predicted observed sensitivity over and above the maternal phenotypes.

In Chapter 4, I investigated the heritability of sleep and cortisol, in order to examine the potential for environmental (i.e., parenting) effects on sleep and cortisol of their children. The heritability of sleep duration, sleep efficiency and wake episodes were 52%, 45%, and 55%, respectively. Common environmental factors played no significant role. High genetic correlations between sleep duration and sleep efficiency and high genetic correlations between sleep efficiency and wake episodes were found. Shared environmental (29%), and unique environmental factors (53%) explained the variance in morning cortisol levels.

In Chapter 5, I examined whether a randomized controlled trial in the form of a brief attachment-based video-feedback intervention (VIPP-SD) increased parental sensitivity and sensitive discipline in parents of school-aged twin children. In our sample with older children, the VIPP-SD did not significantly change observed parental sensitivity or sensitive discipline in the intervention group compared to the control group. The VIPP-SD did improve parents’ attitude toward sensitivity, but not toward discipline.

Chapter 6 expanded the research about VIPP-SD by investigating its effect on children’s hair cortisol levels and conduct problems. In the current pre-registered trial, we randomly assigned 40% of n = 445 families with school-aged twin children to the intervention group. The VIPP-SD was successful in decreasing both children’s conduct problems and hair cortisol levels.

In Chapter 7, I examined whether the transmission of attachment representation is mediated by parental sensitivity and sensitive discipline and whether children are differentially susceptible to parental sensitivity and sensitive discipline. Multilevel structural equation models showed that parental sensitivity, but not parental secure base script knowledge or parental sensitive discipline predicted children’s attachment. This association was moderated by child temperamental discomfort.

In Chapter 8, findings of the previous chapters were discussed.