Roughly half of the difference is explained by genetics but the other half is environmental. A big city full of Democrats is not a healthy place to raise a child for a long list of reasons.
The relative proportion accounted for by genetics versus environment isn’t well determined yet. It probably varies by characteristic. The safest bet, given no further data, is to estimate it at .5 but that’s just an estimate.
I totally agree that a rural environment is the best and safest, assuming the child is kept away from farming pesticides, herbicides and other chemicals. It’s in our genes to want to be close to the earth and not raised in a concrete and asphalt environment.
The smell of the soil stirs the ancient memories of our ancestors. It’s got to be good for our brain chemistry. Just two weeks ago I planted the peas and some cabbage. Just working the soil has to be better than any kind of psychotherapy.