With respect to your first question, I think it would be an overstatement to say fairness is totally environmental. However the environment, or rather people's interaction with it over time seems to matter. Norms tend to be self-reinforcing, so where fairness norms emerged as a result of evolutionary pressures that were no doubt influenced by environmental factors, it makes sense to say fairness took root. The reward mechanism, which is really backward-looking in evolutionary logic, looks to be a greater capacity to organize group activity like agriculture or war. This outcome predictably increased each individual member's chances of passing on their genes. Such evolutionary success can be expected to reaffirm the norms underlying it. I think growth in per capita GDP acts as a reinforcement mechanism in precisely this manner. Where, on average, people feel like they have shared in the overall group success, they are less inclined to challenge the status quo. Add to this the fact that they are the sons and daughters of parents selected on the basis of their fair-mindedness. Obviously, there is a large income disparity in America, home to the population exhibiting the greatest fairness in the study. My essay hopes to offer a plausible explanation for this counterintuitive outcome.

Regarding the second question, I believe the geographical diversity of the sample populations gives good cause to believe that fairness, defined conservatively as an inclination toward equitable distribution of "gifted" wealth, does positively correlate with community size and market integration across cultures. What's interesting to me regarding the culture question is that religion, which appears in the title of the study but really nowhere in my essay, more or less drops out as a significant contributing factor in the fairness of a sample population.