I think the causality is more the other way round. Originally our title was "genetic consequences..." but we were asked to change it. If you look at the part of the paper with coalfields, UK coalfields were laid down about a million years ago, before humans ever came to the area. So that was, loosely speaking, an "instrument" for an environmental variation that might then lead to genetic variation (at area level!)

But yes the key message is, there is geographic clustering at genetic level.

I'm curious how much genetic geographic clustering could have influenced the baseline associations identified in the UK genome wide association studies you selected as a starting point (not sure they typically control for region when associating traits?), particularly with traits like conscientiousness and openness, which obviously can be influenced by polygenic factors, but are also highly influenced by regional cultural variation.