Sarah Schulman:

What makes gay people so ideal as the scapegoat in a family is that they are alone.  Sometimes no one else inside the family is like them or identifies with them.  They become a projection screen, the dumping ground for everyone else's inadequacies and resentments.  In addition, no one else is watching.  No one from the outside will intervene because of the perception that family matters are private and untouchable.  The family structure and its untouchability predominates.  Then, because gay people do not have the full support of their families, they in turn become an ideal social scapegoat.  For, in society, just as in family, no one will intervene.  Society will not intervene in the family, and the family will not intervene in society.  It's a dialogic relationship of oppression.

Ties That Bind, p. 12-13