Over at Crisis, Dale Ahlquist takes the Chestertonian approach to the matter of gay "marriage":

One of the pressing issues of Chesterton’s time was “birth control.” He not only objected to the idea, he objected to the very term because it meant the opposite of what it said. It meant no birth and no control. I can only imagine he would have the same objections about “gay marriage.” The idea is wrong, but so is the name. It is not gay and it is not marriage.

Chesterton was so consistently right in his pronouncements and prophecies because he understood that anything that attacked the family was bad for society. That is why he spoke out against eugenics and contraception, against divorce and “free love” (another term he disliked because of its dishonesty), but also against wage slavery and compulsory state-sponsored education and mothers hiring other people to do what mothers were designed to do themselves. It is safe to say that Chesterton stood up against every trend and fad that plagues us today because every one of those trends and fads undermines the family. Big Government tries to replace the family’s authority, and Big Business tries to replace the family’s autonomy. There is a constant commercial and cultural pressure on father, mother, and child. They are minimized and marginalized and, yes, mocked. But as Chesterton says, “This triangle of truisms, of father, mother and child, cannot be destroyed; it can only destroy those civilizations which disregard it.”

More here.

Catholic social teaching is, in many ways, very simple. You can basically sum it up as, "If it's good for the family, it's good. If it's bad for the family, it's bad." There are a few special exceptions to this rule of thumb, like: "If any one comes to me and does not hate his own father and mother and wife and children and brothers and sisters, yes, and even his own life, he cannot be my disciple." But even that is ordered ultimately toward doing the hard and necessary thing for the good of those we love rather than the easy and expedient thing for the sake of "peace in the family" and any family counselor will tell you how necessary that sometimes is. But, in the main, if you are puzzled by Catholic Social Teaching look at it in that light and pretty much everything snaps into focus. And since the powers and principalities who run our political and cultural institutions are all enemies of the family and, at best, exploiters of "family values" for their own agendas, our political and cultural institutions are always going to be at cross-purposes with Catholic social teaching. That is, of course, until their hostility to the family destroys them. What Catholics need to do is grasp this simplicity and stop getting played by the various political agendas.

This means, among other things, that we must stop pitting concern about abortion and euthanasia against Catholic teaching on social justice as though they are opposites. Catholic social teaching is a whole weave and it is folly to isolate the unborn baby from the family living in poverty, or the desperate teen pressured by family and friends to abort--caring only for the former while caring nothing for what drives the latter to the desperate act of killing her. It is folly to care only about euthanasia, while treating acts of war as something where the guidance of the Church means next to nothing. It is folly to care about gay "marriage"'s destructive effects on the family while paying no attention to individualism's and capitalism's far greater destructive effects on the family. Chesterton, like Catholic Social Teaching, saw that the great mistake we make is to take apart Catholic teaching--including Catholic Social Teaching--and just privilege the bits we like. He refused to do it--which is why he was such a complete thinker.