There can also be differences in chess education. The players from countries of strong chess culture (such as Russia, Ukraine etc.) typically receive strict formal training from early age which may not be case for GM's from other countries.
That sounds convincing. But does Norway have such a strong chess culture? Armenia might since they produced two Petrosians and an Aronian, but I'm not sure. The U.S. surely doesn't, but we produced Fischer.
One of Anand's coach was Dvoretsky
...... The rich man who lives in a mansion and eats expensive foods and lies in bed until noon and parties and drinks and travels around in his private jet and so forth is more likely to die young than the poor man who lives a natural, simple life, eats fresh food, works hard and avoids excesses.
I doubt. The disease that kill men and women is depression. It doesn't choose rich or poor.