Do abandoned children have the right to know their origins?

It has become common practice in the United States, Europe, and worldwide for governments to provide baby boxes or “safe surrender” sites, usually near hospitals, where mothers or relatives of unwanted newborns may abandon them anonymously, so that they may be cared for by others and eventually adopted. Such programs are intended to prevent infanticide and deaths from infant abandonment and have succeeded in doing so around the world. Despite this success, the United Nations has called the provision of baby boxes into question.
http://www.salon.com/2013/02/10/do_unwanted_children_have_a_right_to_know_who_their_parents_are_partne/