Doesn't really make it wrong either... That book of fiction that says it's wrong is in no way the determination of right and wrong.
Right and wrong were around long before the Ancient Hebrew text said "Adultery" was a sin.
"Right and wrong" based on what?
That's the point! You can't determine right and wrong, without a set of guidelines or rules. A standard must be set to make a determination regarding morality.
umm... thats not true love try again. if someone loved another they wouldnt cheat, simple.
Why wouldn't they cheat? What standard says that someone, once married, should remain faithful to his wife?
Who making the rules, here?
as the only one qualified to talk about the brain in this discussion 
, i feel that everything everyone is saying about gayness as a choice is dead wrong.
studies have been conducted, and an area of the brain called the sexual dimorphic nucleus in gay males is similar to that of hetero women, more so then hetero men. this is due to prenatal adrogen exposure.
therefore its not a choice, god made them that way(however, god has nothing to due with controlling the happenings in the universe) so how can he condem them? he cant, its illlogical, therefore its wrong.
gayness is not a sin, preaching hate is.
Then why hasn't this been found BEFORE someone engages in homosexual activity?
If it's a simple case of androgen exposure, why not simply pump the guys with some hormones to fix the problem? You are assuming the "gay wiring" (for lack of a better term) is irreversible.
And, that still doesn't address what I said earlier, regarding gays who were molested as kids and the impact that had on their homosexuality. Nor, does it mention the lesbian factor, as a significant number of them revert to heterosexuality on a regular basis.
With regards to your "preaching hate" spiel, calling something immoral is nothing of the sort. Adultery is wrong; that doesn't mean that people who say such are "preaching hate" toward those who are unfaithful to their spouses.
Again, you can't state that "preaching hate" is wrong, without a standard of morality against which to base such.
Biblically speaking, we have such a standard: When it comes to sexual conduct, any sexual activity outside the confines of marriage (defined as a union between a man and a woman) is immoral, period.
Unfortunately, we don't always follow that standard. But, at least, we know what that standard is.
