Jonathan Daw

Genetic sensitivity to peer behaviors: 5HTTLPR, smoking, and alcohol consumption.

We investigate whether the serotonin transporter–linked polymorphic region (5HTTLPR), a gene associated with environmental sensitivity, moderates the association between smoking and drinking patterns at adolescents’ schools and their corresponding risk for smoking and drinking themselves. Drawing on the school-based design of the National Longitudinal Study of Adolescent Health in conjunction with molecular genetic data for roughly 15,000 respondents (including over 2,000 sibling pairs), we show that adolescents smoke more cigarettes and consume more alcohol when attending schools with elevated rates of tobacco and alcohol use. More important, an individual’s susceptibility to school-level patterns of smoking or drinking is conditional on the number of short alleles he or she has in 5HTTLPR. Overall, the findings demonstrate the utility of the differential susceptibility framework for medical sociology by suggesting that health behaviors reflect interactions between genetic factors and the prevalence of these behaviors in a person’s context.

Defining the Environment in Gene–Environment Research: Lessons From Social Epidemiology

In this article, we make the case that social epidemiology provides a useful framework to define the environment within gene-environment (G × E) research. We describe the environment in a multilevel, multidomain, longitudinal framework that accounts for upstream processes influencing health outcomes. We then illustrate the utility of this approach by describing how intermediate levels of social organization, such as neighborhoods or schools, are key environmental components of G × E research. We discuss different models of G × E research and encourage public health researchers to consider the value of including genetic information from their study participants. We also encourage researchers interested in G × E interplay to consider the merits of the social epidemiology model when defining the environment.

Siblings, friends, course-mates, club-mates: How adolescent health behavior homophily varies by race, class, gender, and health status

Many unhealthy behaviors develop during adolescence, and these behaviors can have fundamental consequences for health and mortality in adulthood. Social network structure and the degree of homophily in a network affect how health behaviors and innovations are spread. However, the degree of health behavior homophily across different social ties and within subpopulations is unknown. This paper addresses this gap in the literature by using a novel regression model to document the degree of homophily across various relationship types and subpopulations for behaviors of interest that are related to health outcomes. These patterns in health behavior homophily have implications for which behaviors and ties should be the subjects of future research and for predicting how homophily may shape health programs focused on specific subpopulations (gender, race, class, health status) or a specific social context (families, peer groups, classrooms, or school activities).

Emerging Adulthood, Emergent Health Lifestyles: Sociodemographic Determinants of Trajectories of Smoking, Binge Drinking, Obesity, and Sedentary Behavior

During the transition to adulthood, many unhealthy behaviors are developed that in turn shape behaviors, health, and mortality in later life. However, research on unhealthy behaviors and risky transitions has mostly focused on one health problem at a time. In this article, we examine variation in health behavior trajectories, how trajectories cluster together, and how the likelihood of experiencing different behavior trajectories varies by sociodemographic characteristics. We use the National Longitudinal Study of Adolescent Health (Add Health) Waves I to IV to chart the most common health behavior trajectories over the transition to adulthood for cigarette smoking, alcohol consumption, obesity, and sedentary behavior. We find that health behavior trajectories cluster together in seven joint classes and that sociodemographic factors (including gender, parental education, and race-ethnicity) significantly predict membership in these joint trajectories.

Nurture net of nature: Re-evaluating the role of shared environments in academic achievement and verbal intelligence.

Prominent authors in the behavioral genetics tradition have long argued that shared environments do not meaningfully shape intelligence and academic achievement. However, we argue that these conclusions are erroneous due to large violations of the additivity assumption underlying behavioral genetics methods - that sources of genetic and shared and nonshared environmental variance are independent and non-interactive. This is compounded in some cases by the theoretical equation of the effective and objective environments, where the former is defined by whether siblings are made more or less similar, and the latter by whether siblings are equally subject to the environmental characteristic in question. Using monozygotic twin fixed effects models, which compare outcomes among genetically identical pairs, we show that many characteristics of objectively shared environments significantly moderate the effects of nonshared environments on adolescent academic achievement and verbal intelligence, violating the additivity assumption of behavioral genetic methods. Importantly, these effects would be categorized as nonshared environmental influences in standard twin models despite their roots in shared environments. These findings should encourage caution among those who claim that the frequently trivial variance attributed to shared environments in behavioral genetic models means that families, schools, and neighborhoods do not meaningfully influence these outcomes.

Life events, genetic susceptibility, and smoking among adolescents.

Although stressful life events during adolescence are associated with the adoption of unhealthy behaviors such as smoking, both social circumstances and physical traits can moderate the relationship. This study builds on the stress paradigm and gene-environment approach to social behavior by examining how a polymorphism in the serotonin transporter gene 5-HTTLPR moderates the effect of life events on adolescent smoking. Tests of interaction hypotheses use data from the Family Transitions Project, a longitudinal study of 7th graders followed for 5years. A sibling-pair design with separate models for the gender composition of pairs (brothers, sisters, or brother/sister) controls for unmeasured family background. The results show that negative life events are significantly and positively associated with smoking. Among brother pairs but not other pairs, the results provide evidence of gene-environment interaction by showing that life events more strongly influence smoking behavior for those with more copies of the 5-HTTLPR S allele.

The contribution of three dimensions of allostatic load to racial/ethnic disparities in poor/fair self-rated health

Objective This study evaluates whether different dimensions of physiological dysregulation, modeled individually rather than additively mediate racial/ethnic disparities in self-reported health. Methods Using data from the National Health and Nutrition Examination Survey (2005–2010) and the Karlson, Hold, and Breen (KHB) mediation model, this paper explores what operationalization of biomarker data most strongly mediate racial/ethnic disparities in poor/fair self-rated health (SRH) among adults in the United States, net of demographic, socioeconomic, behavioral, and medication controls. Results Non-Hispanic blacks and Hispanics had significantly higher odds of reporting poor/fair self-rated health in comparison to non-Hispanic whites. Operationalizations of allostatic load that disaggregate three major dimensions of physiological dysregulation mediate racial/ethnic disparities strongly between non-Hispanic blacks and non-Hispanic whites, but not between Hispanics and non-Hispanic whites. Disaggregating these dimensions explains racial/ethnic disparities in poor/fair SRH better than the continuous score. Analyses on sex-specific disparities indicate differences in how individual dimensions of allostatic load contribute to racial/ethnic disparities in poor/fair SRH differently. All individual dimensions are strong determinants of poor/fair SRH for males. In contrast, for females, the only dimension that is significantly associated with poor/fair SRH is inflammation. For the analytic sample, additive biomarker scores fit the data as well or better than other approaches, suggesting that this approach is most appropriate for explaining individual differences. However, in sex-specific analyses, the interactive approach models fit the data best for men and women. Conclusions Future researchers seeking to explain racial/ethnic disparities in full or sex-stratified samples should consider disaggregating allostatic load by dimension.

The Transmission of Educational Advantage across Three Generations: Grandparent Effects and Spousal Mediation in the Second Generation

The publication of research examining three-generational mobility processes has accelerated during the past half-decade, due in part to new and expanded data that now include large sample sizes of families with more than two generations. However, this area of inquiry is relatively new and little is known about the mechanisms of intergenerational effects beyond parent-child ties. In this article, we draw upon theory and research on intergenerational mobility, maternal education, educational homogamy, and status exchange to propose a new potential mechanism of the transmission of educational attainment from grandparents to grandchildren in the United States: second generation spousal mediation. Using the Panel Study of Income Dynamics, we find evidence that grandparent’s educational attainment positively effects their child’s spouse’s educational attainment net of child’s educational attainment. This pathway then mediates the effect of grandparent’s educational attainment on grandchild’s educational attainment. Further analysis suggests no gender differences in the spousal mediation effect. Overall, this research suggests that grandparent’s educational attainment matters to grandchildren, but is partially mediated through child’s spouse’s educational attainment. We suggest that three-generational transmission of educational advantage is a complex topic in need of further, careful examination of original mechanisms.

Education in 3G: Heterogeneity of Intergenerational Educational Mobility in the U. S.

Following Mare’s (2010) presidential address to the Population Association of America, a great deal of research has been conducted on the dynamics of intergenerational mobility and socioeconomic inequality. Due to this relatively short time span, however, comparatively little is known about the when, where, how, and why of intergenerational effects beyond parent-child ties. In this article, we examine educational attainment across three generations using the Panel Study of Income Dynamics. We find evidence that grandparental education is associated with grandchild education net of parental education, but that association is greatly reduced once spousal education is accounted for – suggesting spousal mediation as a key mechanism of the intergenerational transmission of educational advantage. We also find tentative evidence in favor of the augmentation hypothesis that grandparent and parent educational attainment interactively influence grandchild education. However, the augmentation hypothesis is not supported in spousal mediation models nor in cousin fixed effects models, suggesting that these results may be spurious. Contrary to prior work outside the U.S., we find no evidence of stronger grandparent effects when grandparents were still alive when the grandchild reached age 6. Supporting the claim that genetic transmission may partially explain these relationships, we find weak evidence that grandparent effects are stronger for biological grandparents than non-biological ones. Overall, this research suggests that grandparent’s educational attainment matters, but is mostly mediated through child’s spouse’s educational attainment. We suggest that three-generational transmission of educational advantage is a complex topic in need of further, careful study.Following Mare’s (2010) presidential address to the Population Association of America, a great deal of research has been conducted on the dynamics of intergenerational mobility and socioeconomic inequality. Due to this relatively short time span, however, comparatively little is known about the when, where, how, and why of intergenerational effects beyond parent-child ties. In this article, we examine educational attainment across three generations using the Panel Study of Income Dynamics. We find evidence that grandparental education is associated with grandchild education net of parental education, but that association is greatly reduced once spousal education is accounted for – suggesting spousal mediation as a key mechanism of the intergenerational transmission of educational advantage. We also find tentative evidence in favor of the augmentation hypothesis that grandparent and parent educational attainment interactively influence grandchild education. However, the augmentation hypothesis is not supported in spousal mediation models nor in cousin fixed effects models, suggesting that these results may be spurious. Contrary to prior work outside the U.S., we find no evidence of stronger grandparent effects when grandparents were still alive when the grandchild reached age 6. Supporting the claim that genetic transmission may partially explain these relationships, we find weak evidence that grandparent effects are stronger for biological grandparents than non-biological ones. Overall, this research suggests that grandparent’s educational attainment matters, but is mostly mediated through child’s spouse’s educational attainment. We suggest that three-generational transmission of educational advantage is a complex topic in need of further, careful study.

Gene–Environment Interplay

Although the social and behavioral sciences were long divided over the relative sway of nature and nurture, an emerging field of inquiry, the study of gene-environment interplay, seeks to undermine these distinctions by looking at how these influences on social and behavioral outcomes are interdependent. This article provides a brief overview of three forms of gene-environment interplay: additive genetic and environmental effects, gene-environment correlations, and gene-environment interactions. A distinction is drawn between statistical genetic and molecular genetic models of gene-environment interactions. Finally, a variety of models of gene-environment interactions are described, and the limitations of current research on gene-environment interplay are briefly assessed.