What science has to say about this is irrelevant, folks, unless you’re a consequentialist. And if you’re a Catholic, you had better not be a consequentialist.
If illicit sexual activity caused rainbows to spontaneously burst from everyone’s eyeballs and all our wound-up sexual tension to turn into money, illicit sexual activity would still be illicit. The argument was never “Sodomitical acts cause bad things to happen.” It was “Sodomitical behavior is a bad thing unto itself.”
And if normative sexual activity made everyone grumpy and constipated and poor, well, it’d still be normative and therefore morally laudable. Because the argument was never “marital, noncontraceptive, man-on-woman, intravaginal ejaculatory sex causes good things to happen” (though it does). It was “normative sex is a good thing unto itself.”
Now, bad things often cause other bad things to happen, this is true. But the badness of the bad thing isn’t determined by what comes after it. All of this is true of good things as well. And moreover the fallen (i.e., no longer supernaturally aided) character of human nature means we have a difficult time discerning the consequences of our action, especially how they affect the interior disposition of ourselves and others. So we often struggle and have great difficulties in doing what is right (e.g., dying to ourselves in order to help others, going to Mass in the morning), and often rejoice in doing what is evil (e.g., contraceptive premarital sex, killing people we dislike).
So when we see studies that say things like “Children reared by homosexual couples are better off than those raised by heterosexual couples,” the first thing we need to ask is not “Is this true?” but “According to what standard of ‘better’?” Since science is necessarily naturalist, it’s always going to evaluate “good” and “better” naturalistically, but that’s not meaningful. Natural goods are good but they are not the good. Even if homosexual couples showered their kids with affection and money, there is still one thing they cannot provide their children with, which is good moral example. They are in principle incapable of providing this. Heterosexual couples by contrast are only accidentally incapable of providing it, or any natural good.
Now, these sorts of studies can (CAN) provide us with useful context. They CAN limitedly ratify our intuitions in some respects. That’s about the extent of it. That CAN must be heavily qualified because most social science research is badly done, and I know, because my job is basically to identify bad social science research and I am very, very good at my job. Most people don’t realize that even if a study is conducted with exactly the right analysis and with simple random sampling (i.e., never), the false-positive error rate is about 5%. Since these conditions are never satisfied, it’s probably substantially greater than that.
