I second that she just leave him alone -- 12 years old is just too young to even bring it up unless he comes to you and complains. I would think having a doctor look at it unless, again, if he complained about something wrong, would be humiliating for a child that age.
Imagine if the 12 year old in question were a girl! Just leave the vulva or penis alone unless she or he comes to you saying there is something wrong!! :