This is a theme I revisit from time to time, but I came up with a slightly different explanation of my point than I’ve used before in a Facebook discussion just now, so I’m copying my status and replies:
I don’t know why people on the “Right” don’t want to accept that same sex attraction can be genetic, and why people on the “Left” insist that because it’s genetic, that means it’s good. I have a genetic propensity for my arteries to explode. That doesn’t make it a good thing. DNA was corrupted by original sin: how, exactly, we don’t know, but it’s part of Catholic dogma, and therefore truth.
The “born that way” rhetoric suggests that because people are “born with” a propensity for same sex attraction, that means God designed it and it’s part of Natural Law, but it doesn’t.
Natural Law doesn’t have anything to do with genetics. It has to do with what it means to be a fully realized human being. Natural law doesn’t have to do with “nature” in the sense of science but “nature” in the sense of God’s plan. “Nature” in terms of what science talks about has been corrupted by original sin.
Nature hints at order, but nature itself is not ordered; it is disordered. That’s why I have Marfan syndrome. That’s why some people have Down’s syndrome, heart disease, cancer, alcoholism, etc. It’s why people in general have a compulsion to sexual promiscuity, whereas in a theoretically unfallen race, a man would feel no desire until he saw the woman God intended for him and said, as our first father said of our first mother, “This at last is flesh of my flesh and bone of my bone.”
As it is, we all have disordered inclinations that come from our genes, which have been corrupted by original sin. Some have disordered inclinations for violence; others for lust for the opposite sex; some for gluttony; some for possessions; some of us for all of them. Some people have a disordered inclination that makes them lust for the same sex. The Fathers tell us that we are all blessed with different degrees of virtue and different degrees of these disordered inclinations, and we should not lord it over people that have more challenges in one or another regard.
Thus, Natural Law is not, as many people mistakenly believe, the law of how things work “to begin with,” but just the opposite: it’s the law of how we can make things work the way God intended without original sin. Natural Law is often compared in Catholic ethics classes to agriculture, which in turn is a subset of Natural Law. A good farmer knows how to grow a tomato plant to be the best tomato plant it can be.
The objective fact is that my Marfan syndrome impedes me from being the best person I can be. In some ways, it gives me more of a hurdle to overcome than others have. In other ways, it impedes me from ever achieving some kinds of excellence. I will never be a lumberjack. I will never be a farmer in the true sense of the word, or a cowboy, or a carpenter, or any other work that requires a strong physique. I will never be a star dancer or a star athlete. I admire those who have been blessed with healthy bodies and can achieve these forms of excellence (though I also have a great disdain for the kind of “athletes” and the kinds of “sports” that focus on building up the body only to destroy it because I see them as throwing away God’s gift).
I see homosexuality as the same sort of thing. Some homosexuals can marry (in the proper sense, people of the opposite sex) and have children, and they just have to struggle their whole lives with homosexual temptation the way heterosexual married men often have to battle their whole lives with the temptation to adultery or lust. Others must live in chastity, and are prohibited by their genetic disease from participating in the form of human excellence that is marriage the same way I’m prohibited from sports, but just as I get to pursue a different kind of excellence in my asceticism, so they are called to use their disability to pursue excellence in chastity.