Assessment and coaching have different ground rules. In terms of the details of the person's history, the assessment can be completely confidential.
If the assessment is for the purposes of development within the firm, I give my honest opinion to the person's bosses about the person’s standing on the various dimensions of the assessment. I don't have to share any details of the person's background but I do tell his or her managers what kind of person they are and how they can be most helpful in developing them.
With the person assessed, I reach conclusions and explain the basis for the conclusions.
If I then move onto coaching the person, the only thing I talk about to the firm is whether we are making progress on any of the issues that are important to the firm, or whether the person is doing anything that is a disservice to the firm. See how I handle confidentiality in coaching.
With these new ground rules, once the coaching engagement commences, the person may decide to tell me more about their developmental history knowing that the more complete history I have, the more I can help them.