"one of them had to be gay if you believe in a literal Adam and Eve... whence else diod the genetic component of homosexuality come from?"
There has been no genetic component of homosexuality identified. If you don't believe in a literal Adam and Eve then forget homosexuality, where did original sin come from. Remove a literal Adam and Eve and your problems would really go away. There could be no original sin, therefore you would not need a savior, because you would not inherit the sinful nature from your parents, Adam and Eve, and would not be able to sin. You would still be perfect. We all know that isn't the case though.
"God created us using the same template as he did for animals,"
Scriptures please.
"and our behaviour, biochemistry, psychology and sociology are all deeply coloured by our animal forebears."
Are you saying you are a descendant of an animal and not a special creation of God?
"While I do certainly belief that God calls us to overcome our animal nature in many ways, I do not believe he asks us to do anything that is explicitly against our natures."
The Bible is full of examples of things He asks us to do that are against our sinful natures.
"So if any trait occurs naturally in animals, I see no reason why the same trait isn't reasonably to be expected in humans."
That's because you don't believe humans are a special creation of God.
"Actually the "gay gene thing" as you so eloquently put it, is far more than just a dream, there is enough evidence extant to demonstrate a link between heredity and homosexuality, all that is required now is to isolate the specific codons involved and map their protein expression... but thats really only so much technicality... for all practical intents and purposes, quantitative studies have pretty much confirmed there is a genetic component to homosexuality.
Want links?"
I've seen them already. I've debated this before with someone who is transgendered and waiting to reassign his gender.