France is an interesting comparison. As I understand it, smoking is highly class correlated in the US, but much less so in France. I have a PhD and studied for

France is an interesting comparison. As I understand it, smoking is highly class correlated in the US, but much less so in France. I have a PhD and studied for a time at one of France's premier universities: my advisor smoked, and one graduate student in his lab smoked. All told, probably 10-20% incidence. In America I've worked with or around close to 100 physicists, and only one of them was a smoker.