You are a genetic counsellor. One of your clients, Linda, had a boy with a genetic defect that may have a high recurrence risk, meaning her subsequent pregnancies has a high chance of being affected by the same defect. You offered genetic testing of Linda, her husband, and their son to find out more about their disease, to which everyone agreed. The result showed that neither Linda nor her husband carry the mutation, while the boy inherited the mutation on a paternal chromosome that did not come from Linda's husband. In other words, the boy's biological father is someone else, who is unaware that he carries the mutation. You suspect that Linda nor her husband are aware of this non-paternity. How would you disclose the results of this genetic analysis to Linda and her family? What principles and who do you have to take into consideration in this case?