I have my young brother,our uncle brought him at our home when he was two years old after having disagreements with his girlfriend,we have grown up with him taking him as our last born and right now he is 16 years old but recently someone told him that our Dad is not his real dad,that his real Dad (biological)and the one he is calling mum is not the biological mum is the one he has been calling uncle because the uncle and my Dad are both brothers and this uncle has always been coming home but he has never said anything to this boy,so the boy grew knowing that my mum and Dad are his biological parents ,now someone who is her real sister told her everything from school,right now he is at school but can you please advise me on how me talk to her when he comes back?