A human rights group, the Grandmothers of the Plaza de Mayo, is largely responsible for bringing this issue of the children of the "disappeared" to trial. This group has been dedicated to discovering what happened to their children and grandchildren during the period of military rule.
Interestingly, many of the adopted children identified in recent years have said that they are not interested in finding out about the details of their “adoption” for fear that the parents who raised them may face legal action.
For details about the experience of one of these adopted children, this article from 2004 offers some insight. http://news.bbc.co.uk/2/hi/americas/3585031.stm