Phenotype-environment mismatch due to epigenetic inheritance? Programming the offspring’s epigenome and the consequences of migration
Objective: Epigenetic inheritance has been suggested to be an important factor influencing mortality. We use historical Québec data (years 1670-1759) to study whether parents modify epigenetically their offspring’s phenotype prior to conception in response to predicted/perceived mortality. If yes, those growing in the predicted environment enjoy a phenotype-environment-match which should lower mortality, whereas those growing in a non-predicted environment should have a higher mortality. Methods: We use the large urban-rural mortality differential to capture the predicted/perceived mortality environment. We categorize children into six groups by their migration status: conceived and live in a same environment (urban or rural); conceived in one but born in another environment (urban to rural or rural to urban); and born in one but migrating to another environment by age two. We use Kaplan-Meier survival curves and fixed effects survival models to estimate how child survival up to the age of 15 depends on migration status. Results: Child mortality within families who moved from urban to rural areas does not depend on the child’s migration status. Within families who moved to urban areas the children who were conceived in the rural area but born in the city exhibit the lowest survival. A phenotype-environment-mismatch scenario, however, would result in higher not lower mortality. Conclusion: We do not find evidence for functional (adaptive) epigenetic inheritance. Migration into an environment with lower or higher extrinsic mortality affects child mortality within the families differently than the concept of epigenetic inheritance predicts. The results suggest that epigenetic inheritance may not be important for child mortality among migrants.