I think homosexuality is a normal variant of sexual orientation, just as left-handedness is a normal variant of handedness, and red hair is a normal variant of hair color. I can see that you do not care for that view and I wonder if further discussion might prove fruitless.
My goal here has been to learn more about Catholic views of such topics, and I thank you for contributing to that goal.
Well if everything we become is purely reducible to genes, and normality is measured by their functionality, then to be born with no arms and legs is normal. To develop attraction to children is normal. To develop attraction to animals is normal. There is no real objective value distinction between any potential biological or psychological condition. There is no such thing as abnormality. But that kind of thinking is a product of a naturalistic world-view. You have to begin with naturalism before you can infer those things.
Objectively speaking, Naturalism renders the concept of normality meaningless. Disorder is meaningless given a naturalist world-view. Everything just is what they are; just an expression of energy. If a naturalistic society puts limitations on human actions, it is only in the sense of what one perceives as pragmatically advantages in terms of social, material, and physical survival. In such a society It is no wonder that someone would think that homosexuality is okay.
In a naturalistic world, the gay man defines his sexuality purely in terms of his orientation because that is what he most values. Gender has the least value in terms of defining how a gay person expresses his sexuality (
what he ought to do with it). It is to an extent a meaningless fact that we should happen to be men or women. In fact in a naturalistic world, it would not be abnormal at all for a person to completely change his or her gender identity to what ever he or she felt desirable, because the value of gender is purely subject to the whim of human fancy.
For a christian meta-physician however, value is objective, it is not subject to our whim. The value of sexuality is a given fact. Sexuality objectively begins with the fact that one is either a man or a women, and these things have an intrinsic meaning and value that we are not at liberty to change. We ought to value gender as fundamental to our sexuality and also as the defining factor of what we do with it, if we are to be true to the objective value of what it means to be men or women. Because the value of human sexuality begins with gender, the true value of orientation is only fulfilled insofar as it reflects the value of our gender identity. This is to say that orientation exists as an extension of our sexual identity and not as that which defines it fundamentally. Thus if one truly recognises the objective value of their gender identity, then insofar as they express themselves sexually they will only do that which expresses the value of their gender. If homosexual attraction does not reflect the value of ones gender, then homosexual attraction is by definition a disorder insofar as it impedes the natural end and value of being a man or a women. Homosexual behaviour degrades the complimentary nature of men and women.
Thus in the eyes of a Christian meta-physician, any man or women that acts upon homosexual attraction is immoral insofar as they are degrading their identity as men and women. They are not being true to the value of what they really are. Therefore homosexuality is considered to be a shameful act.
It is for this reason that homosexuality is impossible for Christianity; at least from a metaphysical stand-point.