I had tried for years to help him learn to control his behavior but, in spite of all my efforts, he hadn't learned. For months after he left our family I felt guilty.
Then one day it occurred to me that no matter how good a mother might be, her parenting could never make a physical disability go away. I knew our deaf kids would remain deaf. Other mothers whose children had conditions with no known medical cure would not expect to eliminate their children's special needs by good parenting. Neurological problems and mental illnesses are no different than physical disabilities.
Perhaps there are other parents out there who feel guilty because they can't correct their kids' behavior problems caused by things like that. If so, I hope they will realize, like I did that, as the saying goes, "When all you can do is all you can do, that's all you can do." The most important thing any parent can do is love their children and do the best they can to meet their needs. If they do that, they are good parents regardless of the results.