BROOKLINE, MASS. – It happened years ago, but Deborah Lindeman recounts the moment as if it happened yesterday. Her mother, chastising her, hit her so hard that she left a hand print on her 11-year-old's thigh. Stunned, they both cried for 25 minutes. "We review our lives as parents with some pain, I know we all do," says Ms. Lindeman's mother, Susan Goldstein, who also has a clear memory of when her own father hit her with a belt after she had crossed a street without looking both ways. "I don't like power as a way of solving problems.... We...