Critical Need for Family-Based, Quasi-Experimental Designs in Integrating Genetic and Social Science Research

Abstract

Researchers have identified environmental risks that predict subsequent psychological and medical problems. Based on these correlational findings, researchers have developed and tested complex developmental models and have examined biological moderating factors (e.g., gene-environment interactions). In this context, we stress the critical need for researchers to use family-based, quasi-experimental designs when trying to integrate genetic and social science research involving environmental variables because these designs rigorously examine causal inferences by rigorously testing competing hypotheses. We argue that sibling-comparison, offspring of twins/siblings, in vitro fertilization designs, and other genetically-informed approaches play a unique role in bridging gaps between basic biological and social science research. We exemplify these principles using studies on maternal smoking during pregnancy.

Is the Association Between Education and Fertility Postponement Causal? The Role of Family Background Factors

“…Although within-twin models have a long history in economics (Rosenzweig and Wolpin 1980) and psychology/behavioral genetics (D'Onofrio et al 2013;Neale and Cardon 1992), they have seldom been applied in demography (Amin and Behrman 2014). A comparison of the OLS and the within-twin approach indicates the extent to which family background leads to a spurious association between education and age at first birth.…”

Childhood neurodevelopmental problems and adolescent bully victimization: population-based, prospective twin study in Sweden

“…To the extent this association is not unity within pairs, it implies the influence of the non-shared environment. As mentioned in the introduction, the non-shared environmental effect (E) may be interpreted as a quasi-causal parameter, that is, an association that persists after controlling for all potential genetic and shared environmental confounds (26,27). In the context of this study, a significant E parameter would indicate that within a twin pair, the twin who displayed more NDPs at age 9 would also be bullied more at age 15, which cannot solely be attributed to genetic or shared environmental factors.…”

“…Specifically, within a monozygotic twin pair, if the twin with more NDPs tend to suffer from more bully victimization, then the association cannot be attributed to unmeasured genetic and shared environmental confounds. If, on the other hand, both twins within a pair suffer from an equal amount of bully victimization regardless of who had more NDPs in childhood, then a causal interpretation is untenable (26,27). In other words, in such a case, the phenotypic association is driven by genes and/or shared environments.…”

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

“…Gardner, Burton & Klimes, 2006;Kaminski, Valle, Filene & Boyle, 2008). Alternatively researchers can employ naturally occurring quasi-experiments involving groups of individuals that differ in their genetic and/or environmental relatedness (for reviews of the many research designs capable of controlling for familial confounds see D 'Onofrio & Lahey, 2010;D'Onofrio, Lahey, Turkheimer, Lichtenstein, 2013;Horwitz & Neiderhiser, 2011;Rutter, Pickles, Murray & Eaves, 2001). That is, the degree to which their genome and environment correlate.…”