Writing for Family Studies, W. Bradford Wilcox reports the negative trends for marriage have leveled off, undoubted good news. He makes much of the finding that two parent families are more important for the raising of boys than of girls. It is good to know the data support this view but I don't find it at all unusual.
After all, most one-parent households are headed by a woman. Girls growing up in that environment have a role model, an adult woman taking responsibility for the well-being of others. Boys in that environment learn men are expected to be irresponsible, inconstant, intermittent visitors ... ships passing (DNA) in the night, as it were. No surprise boys grow up to replicate the behavior.