In our analysis of possible relationships between average phenotypes for worldwide populations and average polygenic scores for those populations, we chose to examine height because it is easily measured and because factors affecting height (e.g., nutrition) are also relatively easily quantified. In contrast, research on other variables such as weight, smoking status, psychological symptoms, and cognitive performance requires more careful control for environmental confounders (including variables like social status), which are often correlated with ancestry and therefore may also be correlated with global principal components and polygenic scores (as currently calculated). This means that confounding of environmental and genetic effects is likely. For example, social experiences such as being subjected to racism are prime candidates for confounding in genetic studies.
