DOES DIVORCE HURT KIDS? Not so very much, says the latest major study. But it contradicts the one before it, so who's right? Here's an old bit from a stand-up comic's act: "Some say the glass is half empty. Some say it is half full. I say it's twice as big as it needs to be." This is a story of glasses, not nearly empty, not quite full. Except that the glasses are the children of divorce--a million new ones each year in the U.S.--and what's being measured is their misery. For decades, since a pioneering study by J udith S. Wallerstein in 1971, sociologists and family-health specialists have posited that the wrenching act of divorce and its aftermath leave scars that can linger--in the afflicted children, throughout adolescence and into adulthood. This theory, buttressed by Wallerstein's 2000 best seller, The Unexpected Legacy of Divorce: A 25 Year Landmark Study, helped explain so many ills--depression, juvenile delinquency, poor grades--even a