.. do we really want to argue that because a behavior occurs in the animal world, that behavior should be validated in humans?...
Not suggesting that the behavior is validated. Just indicating that such behaviors do occur elsewhere in nature. Note that while some of these behaviors can be attributed to dominance (its not gay if its angry sex...), there are good examples of actual long-term coupling in a number of species even in cases where both sexes were present and available. Many who come out against homosexual behavior do so because they see it as "unnatural". Well, if we see it occurring in so many other species, may be it is not so unnatural. May be there is a reason for it, though we may not understand what that reason is yet.

That also addresses some of Don's comments on environment (i.e., nature vs. nurture stuff). Homosexual behavior is seen in a wide variety of animals, and in a wide variety of different upbringings; therefore suggests that it is more of a natural thing that upbringing.

.... Humans are not animals...
Incorrect. Humans are part of the animal kingdom (Kingdom Animalia, if you want to get specific). Just like all other life on the earth, we evolved from a common ancestor. We share more than just board similarities with other species. Consider the basic building blocks of life: RNA and DNA. We have something in common with all life here on earth. That is because all life is related through a common ancestor.
No offense, but trying to derive scientific facts from the bible will provide incorrect answers. The bible was written by nomadic sheep herders a couple thousand years before the advent of modern scientific methods and cannot be expected to be an authority on science.

...Could I participate in those activities?? No way no how....
I think you will find that is the answer for anyone who is straight. As Hlleonard indicated, that is not really a choice on your part, it is who you are. Same for a homosexual. The thought of being with someone of the opposite sex disgusts them in the same way the thought of being with someone of the same sex. I would have to look around to see if there were any studies on this (most likely are). I have based my comments on conversations that I have had with various homosexuals over the years.