The project has made substantial progress since the start, with four papers published in high-ranking interdisciplinary journals, one book chapter, as well as ten research papers under review. In addition, we have contributed to a government report about the use of molecular genetic information in areas beyond health and health care and written five policy pieces about the role of the nature-nurture interplay in shaping individuals’ outcomes. The project has also made substantial progress on an exciting new data source, digitizing large amounts of historical local area-level data for England and Wales over a 40-year period.
More specifically, we have created software that has already allowed us to digitize over 40,000 pages of historical local area-level data from the 1940s to the 1970s. These data can in turn be merged with existing data at the individual and/or regional level. For example, we have shown the extent to which two UK measles vaccination campaigns introduced in the 1960s reduced measles rates across the country, how this reduction had some long-term impacts on the health outcomes of those exposed to the vaccination campaigns, and how these impacts partially depend on individuals’ genetic variation. Similarly, we have documented the long-term cardiovascular impacts of more general adverse early-life environments, captured by one’s infant mortality rate in the year and local area of birth. Our results are consistent with the original Barker hypothesis, but we show considerable genetic heterogeneity in this relationship: in areas with the lowest infant mortality rates, the effect of one’s genetic predisposition effectively vanishes.
Our research has also shown how the early life nutritional environment is crucial in shaping individuals’ economic and health outcomes in later life, and how it interacts with individuals’ genetic ‘predisposition’ for the economic and health outcomes. Our work highlights the long-term impacts of prenatal exposure to sugar confectionery on one’s later life health and educational outcomes. Our results are consistent with the developmental origins hypothesis, suggesting it is advantageous to be exposed to a prenatal environment that is more aligned with the postnatal environment.
Furthermore, we have quantified the adverse impacts of prenatal and early childhood exposure to severe pollution for individuals’ later life economic and health outcomes. We show that children who were exposed to excessive pollution in early life have substantially lower intelligence scores and worse respiratory health, with some evidence of a reduction in years of schooling. Furthermore, we show that these effects are stronger for those genetically ‘predisposed’ to these outcomes.
We have also shown the importance of parental investments in child development, and how this is moderated by individuals’ genetic ‘predisposition’. Following the literature, we use an individual’s birth order as a proxy for parental investments and interact that with one’s polygenic score for educational attainment. Using a sample of full siblings, we show that the additional parental investments associated with being firstborn are more effective for those who randomly inherited higher genetic endowments for education.
We have also explored the use of molecular genetic data from a more methodological perspective. We have highlighted two implications of the fact that polygenic scores are measured with error. First, it leads to bias in the effect estimates in regression models; second, it affects individuals’ ranking in the polygenic score distribution which can impact on clinical decision-making if treatment decisions are made (partially) based on individuals’ genetic data (i.e. personalised interventions). We show the importance of both empirically as well as via simulations and offer a solution to the issue of attenuation bias.
