When parents have a mix of successful and not-so-successful adult children, the heartache they suffer over one dysfunctional kid's problems isn't offset by positive feelings from the accomplishments of their other offspring, a new study finds. "One bad apple really does seem to spoil the barrel," said Adam Davey, associate professor of public health in the College of Health Professions and Social Work at Temple. "What this study shows is that it takes many successful children to offset the negative consequences of one child with problems." Davey's advice to parents: Try to step back and not be as involved in your grown children's lives.