Here is an article that compiles a lot of the extensive research that shows that homosexuality has a genetic link. They have studied everything from rams to fruit flies and found conclusive genetic differentiation in those animals that prefer the same sex.
http://seattletimes.nwsource.com/html/localnews/2002340883_gayscience19m.html
Another article specifically about rams:
http://www.scienceblog.com/cms/node/2421
Homosexuality has been continuously observed and studied in the animal kingdom. In Amsterdam, there is even a zoo that contains only gay animals:
http://www.ananova.com/news/story/sm_43383.html
Part 2
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Even if you consider yourself a devout Christian, that is no reason to deny evidence that exists in the world around you. The Bible is not an "all or nothing thing" it is a complex compilation of moral parables and cultural histories that were written over the span of thousands of years by many different authors. There isn't a single person that believes/practices every single thing promoted in it in a literal fashion. For example, if you took everything it said literally, you would be required to believe that:
1) The sun revolved around the earth - Joshua 10:12 (among many others)
2) The earth was flat and had corners. - Isaiah 11 & Revalation 7 (among many others)
3) differing accounts of who was there when Jesus rose from the dead:
Mathew 28 1-10 (the two different Marys are present")
John Chapter 20 (Only Jesus' Mother Mary by herself)
Mark 16 (only Mary Magdalene)
4) differing accounts of Jesus' last words - Mathew 27, Luke 23, and John 19
5) that woman must keep their heads covered in church, must remain quite, and subservient to men - 1 Corinthians 11
6) that the moon is its own source of light - Isaiah 13:10
7) that slavery is moral and slaves must obey their earthly masters - Ephesians 6-5
8) that it is sinful to eat corn that hasn't had the corners rounded off and destroyed first.
Of course nobody believes all of these things because we generally realize, even if we take the overall message of the Bible as containing moral truths, that the Bible itself is not an infallible book and that it contains a lot of passages that are specific to a particular cultural context, others that are allegorical, and others that have conflicting accounts of events. It doesn't have to be an "all or nothing" thing, and, if you want to maintain an intellectually honest faith, it obviously can't be. So there is no real point justifying bigotry because "the Bible says" because the "the bible says" alot of things which you don't practice or believe.