Why is America so rich and powerful? The answer lies in our genes, according to psychologist John Gartner. Hypomania, a genetically based mild form of mania, endows many of us with unusual energy, creativity, enthusiasm, and a propensity for taking risks. America has an extraordinarily high number of hypomanics--grandiose types who leap on every wacky idea that occurs to them, utterly convinced it will change the world. Market bubbles...