How do we know “God’s Will” in this case?
We are members of Christ’s Church. God’s will is made known to us by Revelation. Revelation is contained in Sacred Scripture, Sacred Tradition. The Magisterium of the Church is the authority established by God to guarantee the preservation and transmission of God’s Revelation in both its ordinary and extraordinary teaching.
Same-gender preference animals appear in nature, so it follows at is part of “natural law” as it comes through what is seen in nature.
Adam and Eve’s sin affected not only human nature (robbing us of eternal life, the preternatural gifts and subjecting us to concupiscence), it produced a “ripple effect” that spread outward from the human race and disordered all of God’s creation. It is not surprising then that the disorders which afflict our baser nature should also afflict the natures of animals.
Cancer, Down’s syndrome, schizophrenia, bi-polar disorders, etc. are all “natural” insofar as they all “appear in nature” too, yet we seek cures for these disorders; we do not subject them to a senitmental whitewash and try to pretend that they are not debilitating disorders.
I described it more than just emotion and sentimentalism. The connections are as true as different-gender relationships. The strength of the mating connection is as strong as it is for both same-gender and different-gender relationships (which means some succeed, some fail, and there are lots of ups and downs inbetween).
The mating desire is present in all human beings, I agree. Human beings pair up because "“it is not good for the man to be alone” (Gen 2: 18), but this desire was placed in man by God, and ordered by Him toward the opposite gender. When this desire manifests itself in a man as a desire for another man, it is a disordered desire and it must be rejected. If a man pairs with another man, or a woman with another woman, the emotional behaviour will
mimic that of a person involved in a heterosexual relationship of course, but it is a deceit. However deep or pleasurable a man’s emotional attachment to another man may be, it remains a disordered manifestation of an otherwise good desire.
Sexual preference (having and acting on it) is not a defining personal matter and not sinful.
The rainbow flag crew seems to disagree with you. Anybody who insists that the rest of us relate to them as “gays”, “lesbians”, “bi’s”, “queers”, “transgendered” etc., etc.
ad nauseum is certainly defining themselves in terms of their favourite, perverted genital activity and disordered identity. And anyone who’s ever been treated to immoral spectacle of a “Gay Pride” parade has no doubt as to what the defining element of their identities are for the infantile and narcissistic personalities that stage such events.