Genetic influences on social life : evidence, pathways, and implications for sociological inquiry

Scholars in diverse disciplines are currently engaged in debates concerning the causes and consequences of human social interaction in areas including personality development, interpersonal characteristics, social attachments and support, family life, religious involvement, civic engagement, socioeconomic attainment, and health and wellbeing, among others. Unfortunately, researchers in these areas are compartmentalized into two, largely isolated, camps: (1) social scientists who base their research on the assumption that social outcomes are primarily, if not exclusively, the products of social-environmental influences; and (2) biologists, geneticists, psychiatrists, and some psychologists, all of whom assume that genetic factors are important as well. The purpose of this dissertation, therefore, is to begin integrating sociological and biomedical research on social life. To facilitate this task, four specific research questions are addressed: Do genetic and environmental factors both influence social life, and if so, what is the relative contribution of each? Why and how do genetic factors influence social life, and what are the pathways by which they operate? Are genetic and environmental influences on social life correlated (i.e., non-additive), and do genetic factors bias social scientific studies that do not take them into consideration? Do genetic and environmental factors interact to produce social outcomes? To answer these questions, twin sibling data from the National Survey of Midlife Development in the United States (MIDUS) is analyzed. In response to the first question, results reveal that both genetic and environmental factors are indeed important predictors of individual-level variation on several different aspects of social life, including religious involvement, civic engagement, personality and interpersonal characteristics, family relations, socioeconomic status, community attachment, neighborhood quality, and psychological distress. Further, genetic effects on several of these outcomes (e.g., civic engagement, psychological distress) are mediated by personality, interpersonal characteristics, and social relationships, which provides insight into the second and third research questions. With respect to the final question, the findings presented here suggest that genetic and environmental influences on at least one social outcome--health and well-being--function in both a correlated and interactive manner. Overall, the theoretical and empirical research provided in this dissertation highlights a growing need for research that integrates sociological and biological approaches to the study of social life.