I already explained the reasoning for the question. You need to look up mating behavior and the strength of its influence on behavior.
No assumption needed. You haven't disproved the point.<quoted text>
Ok fine, lets make believe for a moment that you haven't been talking out of your asshole. Let's say you "Expose the defect of homosexual orientation." as you put it. Ok now what. Tell me why it matters. If two people are wired wrong or "defective" what do you care? How does it bring harm to anyone for them to marry? The handicapped are allowed to marry, hell even mentally handicapped people can marry. So "defect" and "unnatural" don't really cut it.
The only reason to prevent SSM is if it causes identifiable harm. All this nonsense about mating behaviors is irrelevant.
Here is why it matters. Words describe reality. Accuracy makes us safe and happy. Inaccuracy is called denial. It is dangerous not only for the person in denial, but all those around him. An example would be labeling arsenic 'sugar'.
In your example, you are equating genetic defects, but denying the gender distinctions. This is exactly why I encouraged you to read up on mating behavior.
Once again, if you look at the most basic essence of marriage, it is a cross cultural constraint on evolutionary mating behavior. Not only is it impossible to equate gay couples to marriage, they are diametrically opposed to each other.
I appreciate an honest question.