Thursday, July 12, 2018

Genetic Analysis Of Social Class Mobility

pnas |  Our analysis suggests three take-home messages. The first take-home message is that genetics research should incorporate information about social origins. For genetics, our findings suggest that estimates of genetic associations with socioeconomic achievement reflect direct genetic effects as well as the effects of social inheritance correlated with genetics. Future genetic studies of social attainment can refine inferences about direct genetic effects by including measures of social origins in their study designs. The same is true for genetic studies of other phenotypes, because childhood socioeconomic circumstances are implicated in the etiology of many different traits and health conditions (5456). Such analysis will help clarify interpretation of studies that analyzed GWAS data and found evidence of genetic overlap between educational attainment and several biomedical phenotypes (57, 58). The advent of national biobanks and other large genetic datasets is increasing the power of GWAS to map genetic risks. Research to investigate how much of the genetic risk measured from GWAS discoveries arises within a single generation and how much accrues from social inheritance correlated with genetics across successive generations is needed.

The second take-home message is that social science research should incorporate information about genetic inheritance. For the social sciences, our findings provide molecular evidence across birth cohorts and countries of genetic influence on social attainment and social mobility. This evidence supports theory in the social sciences that frames genetics as one mechanism among several through which social position is transmitted across generations (9, 20, 21, 59). These theories imply that genetic factors can confound estimates of social environmental effects. However, because genetics have been difficult to measure, studies addressing these theories have had to estimate genetic contributions to attainment indirectly, while other social science research has simply ignored the problem. Now, genetically informed theories of social attainment and mobility can be revisited, tested, and elaborated using molecular genetic data available in an ever-growing array of genetically informed social surveys and longitudinal cohort studies.

Beyond theory, integration of measured genetic inheritance into research on social mobility can add value in at least three ways. First, genetic controls can improve the precision of estimates of environmental effects (11, 14), e.g., of how features of parents’ social circumstances shape children’s development. Second, genetic measurements can provide a starting point for developmental investigations of pathways to social mobility (16, 60), e.g., to identify skills and behaviors that can serve as targets for environmental interventions to lift children out of poverty. Third, genetic measurements can be used to study gene–environment interplay; e.g., how policies and programs may strengthen or weaken genetic and nongenetic mechanisms of intergenerational transmission (61). In our analysis, modeling effects of social origins attenuated genetic-effect sizes by 10–50%, depending on the outcome and cohort. This variation is consistent with evidence that genetic influences on individual differences may vary across cultures and cohorts and across stages of the life course (62, 63). Research is needed to understand how molecular genetic effects on socioeconomic attainment may operate differently across environmental, historical, or economic contexts and the extent to which they may wax or wane across adult development.

The third take-home message is that genetic analysis of social mobility can inform programs and policies that change children’s environments as a way to promote positive development. The genetics we studied are related to socioeconomic attainment and mobility partly through channels that are policy-malleable. Personal characteristics linked with the attainment-related genetics we studied involve early-emerging cognitive and noncognitive skills, including learning to talk and read, act planfully, delay gratification, and get along with others (10, 16). These skills represent intervention targets in their own right, for example by policies and programs that safeguard perinatal development and provide enriching, stable family and educational environments (64). A significant contribution of our study is that the nongenetic social and material resources children inherit from their parents represent a further mechanism linking genetics and attainment over the life course. Policies and programs cannot change children’s genes, but they can help give them more of the resources that children who inherit more education-linked genetics tend to grow up with. Our findings suggest that such interventions could help close the gap. The next step is to find out precisely what those resources are.

A long-term goal of our sociogenomic research is to use genetics to reveal novel environmental intervention approaches to mitigating socioeconomic disadvantage. The analysis reported here takes one step toward enabling a study design to accomplish this. We found that measured genetics related to patterns of social attainment and mobility, partly through direct influences on individuals and partly through predicting the environments in which they grew up. Specifically, parents’ genetics influence the environments that give children their start in life, while children’s own genetics influence their social mobility across adult life. As we learn more about how genetics discovered in GWAS of education influence processes of human development that generate and maintain wealth and poverty, we can identify specific environments that shape those processes. Ultimately, this research approach can suggest interventions that change children’s environments to promote positive development across the life-course.