PARENTS matter. That’s the message of Susan Mayer’s new book, What Money Can’t Buy. † The University of Chicago sociologist’s sophisticated and often ingenious analyses lead her to conclude that parents’ characteristics are more important than their income in determining how well they raise their children and, hence, how well their children will do in later life. Thus Mayer argues that giving low-income families more money would not help their children very much. Such conclusions are likely to infuriate liberals and receive an “I told you so” response from conservatives, but it’s more complicated than that.