For example, when you compare the "advanced countries" and "developing countries", you are comparing two different races (asian vs. black). I think happiness is mainly decided by genes. Genes are closely correlatd with race. Some races are much happier than others. (for example, if you compare suicide rate, you will see asian:white:black = 8:4:1. I am not sure about the number 1, but it is the lowest for sure.).