Economic prosperity and "the two-biological-parent family"

Over at Public Discourse, William Jeynes argues that "the surge of non-traditional family structures has unleashed deleterious forces upon the American economy for nearly five decades."  The essay's title and intro emphasize the relationship between economic prosperity and "the two-biological-parent family."  The essay itself, though, focuses on broken homes and the rise of single parenting.  The essay reflects, in my view, a recurring flaw of many anti-SSM arguments, as there is a tendency to be a little too quick to use evidence of ills associated with single parenthood as evidence of ills associated with all non-traditional family structures.  There is no dispute that single parenthood creates economic hardships for the kids and the broader society.  But we need additional evidence to make the jump that families headed by a same-sex couple create the same economic hardships.