Marriage may be more beneficial to children than we have known.Some interesting recent research is indicating that children from married families have higher rates of high school graduation than those from divorced or single-parent families. This was a stronger factor in determining graduation rate than child poverty, race and ethnicity.
Additionally, boys from married families tended to have more similar rates of school achievement compared to girls. When boys live in a single parent or divorced family, their school achievement (even through college) is significantly lower than girls.
One can find a summary of this research, and links to the original studies, here: