I have often wondered if everyone who can procreate children really does make the best parent for the child.
Humans have no inate behaviors, so I am told by sources other than holy writ's, and as a result must learn how to procreate children and parent children.
The two skills are not the same.The same sources (scientists) say that animals do have unlearned, "imprinted" behaviors that are referred to as instincts. Those who are not properly imprinted for the parenting instinct do not let the problem survive another generation, their young rise high on some other animals' dinner menu through neglect or other more direct action.
The moralists could of course say that gay, lesbian or trans people have learned our behaviors on those subjects, and thereby they negate the purity of their argument that there are no gay animals, since comparing humans to animals, ie imprinting to learning is reductio ad absurdum, since it boils down to humans who need to learn are animals who don't need to learn.
Try the logic at a cocktail party where good Baptists and Pentecostals are hitting the martini's, but stay on tonic water and lime yourself until the fun is over.