“The tenuousness of modern life can make anyone feel overwrought. And in societal moments like the one we are in — thousands losing jobs and homes, our futures threatened by everything from diminishing retirement funds to global warming — it often feels as if ours is the Age of Anxiety. But some people, no matter how robust their stock portfolios or how healthy their children, are always mentally preparing for doom. They are just born worriers, their brains forever anticipating the dropping of some dreaded other shoe. For the past 20 years, [Jerome] Kagan and his colleagues have been following hundreds of such people, beginning in infancy, to see what happens to those who start out primed to fret. Now that these infants are young adults, the studies are yielding new information about the anxious brain.

These psychologists have put the assumptions about innate temperament on firmer footing, and they have also demonstrated that some of us… are born anxious — or, more accurately, born predisposed to be anxious. Four significant long-term longitudinal studies are now under way: two at Harvard that Kagan initiated, two more at the University of Maryland under the direction of Nathan Fox, a former graduate student of Kagan’s. With slight variations, they all have reached similar conclusions: that babies differ according to inborn temperament; that 15 to 20 percent of them will react strongly to novel people or situations; and that strongly reactive babies are more likely to grow up to be anxious.” (New York Times Magazine)