IMPLICATIONS FOR FUTURE RESEARCH

To conclude, we return to our initial questions. First, to what extent are sex and gender incorporated into research on genetics and health? Second, how might social science understandings of sex and gender, and gender differences in health be more fully integrated into scholarship in this area? Our systematic review suggests that although sex is frequently included as a control or stratifying variable, few articles articulate a conceptual frame or methodological justification for conducting research in this way. Most studies are not motivated by sex or gender differences in health; sex, when it is considered, is secondary, and gender (as a concept reflecting social variation) is most often ignored.
We argue that making the connection between sex-linked biological variation and gender differences in health outcomes will benefit from greater attention to the intertwining of social and biological variation over the life course. We also suggest that gender differences in health can result when genetic variants are expressed in different contexts, biological or social, including “gendered” or “sexed” environments. Growing evidence suggests that the relationship between genetic factors and health outcomes are conditioned by environments. We argue that gender needs to be recognized as a dynamic social, cultural, and institutional environment. In an investigation of the heritability of resilience, results are suggestive that such a direction may be productive; resiliency, which is overall equally heritable in men and women, manifests more in men, which the authors suggest could be based in group-level differences in environmental mastery.50
Research to date suggests not only that biological factors are key pathways linking sex or gender and health, but also that they operate in concert with social behavioral factors to produce sex- and gender-specific variation in disease and mortality patterns. Future studies will benefit from adopting a multi-systems approach to explicate the complex processes underlying such differences across levels of organization, including the biology at the cellular, organ, developmental, behavioral, and contextual levels.14 Such a change is necessary for understanding the multiple forces that shape sex differences in both physiology and behavior in particular and that are essential for understanding and finding solutions to problems arising from reciprocal interactions between a person’s social and physical worlds in general. Genetic factors are an integral component of this system and understanding how genetic activities contribute to these reciprocal interactions between a person’s social and physical world is essential.
In addition, future research would benefit from adopting a life course perspective with an emphasis on age variations.51 Studies of complex age dynamics of sex-mortality differentials in nonhuman species such as medflies, savannah baboons, and other mammalian and non-mammalian species contribute knowledge of biological and genetic explanations to sex-specific variation in specific animal populations and might inform studies of sex-specific variation in health in humans.52–54 The recent explosion of new biological information, including samples that can be used to study the cellular and molecular mechanisms of human biology in large population-based surveys, offers opportunities for epidemiologists and other population scientists.55 Likewise, the recent interest and movement in the genetics community toward collecting longitudinal data from large cohorts, and developing standard measures of phenotypes, and a host of environmental factors, presents complementary opportunities for biologists, geneticists, and other natural scientists.56 Taken together, these developments reflect broad interest in an integrated science of human health.
In this context, the leading questions for a new era of integrative social and biodemographic research on sex and gender differentials in health and longevity include: What are the major markers of intrinsic biological robustness that relate to sex-specific disease and aging processes? How do social exposures and aging processes operate independently and together to alter such robustness? How can we deepen our understanding of sex and gender differentials in health by better situating genetic processes in their dynamic, multilevel social and biological contexts? Answers to these questions will have important scientific and policy implications for reducing social disparities in health and mortality. At the same time, approaching them will require an integrative explanatory framework that bridges the social and biomedical sciences.
This framework should allow us to first identify sex-specific variation in major aspects of biological structures and functions as well as social factors, model how these differences contribute to sex and gender differentials in health, and more importantly, elucidate the interconnections of biological parameters and social factors in these models. This integrative framework can further address the gap in previous research by adopting a life course perspective. It should allow us to transform knowledge on the additive and interactive social, biological, genetic, and behavioral pathways that lead to disease by linking sex- and gender-specific risk to physical and social exposures that occur over time, during gestation, childhood, adulthood, and old age. Such integration promises to advance understandings of gender differences in health, and may well yield insight regarding the processes and circumstances that make genetic variation relevant for health and well-being.