Accounting for genetic and environmental confounds in associations between parent and child characteristics: A systematic review of children-of-twins studies.

Abstract

Parental psychopathology, parenting style, and the quality of intra-familial relationships are all associated with child mental health outcomes. However, most research can say little about the causal pathways underlying these associations. This is because most studies are not genetically informative and are therefore not able to account for the possibility that associations are confounded by gene-environment correlation. That is, biological parents provide not only a rearing environment for their child but also contribute 50% of their genes. Any associations between parental phenotype and child phenotype are therefore potentially confounded. One technique for disentangling genetic from environmental effects is the Children-of-Twins (CoT) method. This involves using datasets comprising twin parents and their children to distinguish genetic from environmental associations between parent and child phenotypes. The CoT technique has grown in popularity in the last decade and we predict that this surge in popularity will continue. In the present article we explain the CoT method for those unfamiliar with its use. We present the logic underlying this approach, discuss strengths and weaknesses and highlight important methodological considerations for researchers interested in the CoT method. We also cover variations on basic CoT approaches, including the extended-CoT method, capable of distinguishing forms of geneenvironment correlation. We then present a systematic review of all of the behavioral CoT studies published to date. These studies cover such diverse phenotypes as psychosis, substance abuse, internalizing, externalizing, parenting and marital difficulties. In reviewing this literature we highlight past applications, identify emergent patterns, and suggest avenues for future research.Keywords: children-of-twins; gene-environment correlation; intergenerational transmission; parenting; psychiatric epidemiology.Theories of parenting propose that parents impact the development of their children in a variety of ways: At one level parental characteristics are predictive of child characteristics -many traits tend to run in families and this is often interpreted as evidence for the impact of parent behavior on child development. For example, anxious parents often rear anxious children (Murray et al., 2008) and it has been suggested that this is because children learn such behavior from their parents (Murray et al., 2008;Rachman, 1977;. Proponents of social learning theory (Bandura, 1977) might suggest that this learning occurs via processes of imitation and modelling, and evidence also indicates that the learning process can be more direct and involve the verbal transmission of information from parent to child (Field & Purkis, 2011).Although children may learn behaviors through imitating and listening to their parents, parents often seek to influence their children's behavior in more direct ways, through the parenting behaviors that they direct towards their child. For example, the punishment and praise of chil...

Genetic transmission of reading ability

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The Intergenerational Transmission of Anxiety: A Children-of-Twins Study

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