So we've looked at how homosexuality has been distorted in the Bible. However, for those that don't readily accept literal translations of the Bible or need a little extra nudge to accept something they don't fully grasp, there a few scientific finding and theories that can shed some light on non-reproductive sex of the homosexuality variety. History has shown us that homosexuality is far from a new phenomenon. It has been around since the beginning, sometimes persecuted, sometimes advised, but always controversial in some part of the world. In ancient Greece, they did not see sexual identity as social identifier. In fact, young boys would go off with prestigious men of the community in a "rite of passage" of sorts. This practice was called pederasty (Chimos) and it didn't seem to lead to a majority of young men growing up to be homosexual; the Greek boys grew up and the culture lived on through reproduction. If there were any conditions for breeding homosexuality, wouldn't that be one of them?
There has always been a debate in nature vs. nurture. Was Michele Bachmann born looking like one of those paintings whose eyes follow you wherever you go no matter where she's looking or was it a result of trying to teach her algebra? Things of that nature. Well, I checked this stat out and a staggering 47% of Americans believe homosexuality is merely a life choice. Before we get into the biology and genetics of homosexuality, let's first just address how silly that sounds when you think about it for 2 seconds (yes, that means turn off Real Housewives).
Studies have shown GLBT youth are five times more likely to attempt suicide than their heterosexual peers in a study of 11,000 11th grade students in Oregon. After delving deeper into this, policies in schools to protect GLBT youth lowered suicide rates for ALL students involved in the study . Why, oh why, if you knew that your life was going to be more difficult and you would face relentless ridicule and torment would you willingly make the "choice" of being homosexual? Why, oh why, would you subject yourself to hormone replacement therapy, intensive counseling, and pay a large sum of money for a sex change unless you were ABSOLUTELY sure that your brain was either masculinized or feminized and didn't match the genitals you were sporting? It is positively ridiculous to believe that anyone would willingly change their sexual orientation to invoke the kind of ostracism that accompanies coming out of the closet in many social circles.
You'd think if there was any biological basis for homosexuality, there would be physical differences between homosexuals and heterosexuals that were inexplicable by social causes. Here are some of them:
1. INAH3: clusters of the hypothalamus in particular the third interstitial nucleus of the anterior hypothalamus (INAH3) were discovered in a small sample size in 1991 by Simon Levay to be smaller in gay men than in straight men. In fact the the INAH3 in gay man were very similar in size to that of a heterosexual woman. This area of the brain is differentiated prenatally. 
2. Gay men have been found to be attracted to different odors than straight men. 
3. Gay men report slightly longer, thicker penises than straight men (unfortunately for the bottoms) 
4. Gay men's brains respond differently to fluexotine than straight men. 
5. Homosexuals are significantly more likely to be left-handed or ambidextrious which is determined prenatally. 
Outside of just the physical differences between homosexuals and heterosexuals found by science, have you ever talked to a gay guy? I mean it doesn't take a Stephen Hawking to buzz that Perez Hilton isn't of the same breed as Duane Chapman. Here are some more interesting studies:
1. Ovulating women are better at detecting a male's sexual orientation. 
2. An interesting study linking genetics to sexual orientation and gender conformity in women, suggesting that mental states could affect prenatal exposure to androgens. 
3. Deleting a single gene in mice can turn straight female mice into Ellen Degeneres. Not conclusive, but interesting nonetheless. 
Basically, I'm trying to relay two points. The first is that even though we have not identified a single genetic pathway to homosexuality, yet, doesn't mean it isn't painfully obvious of the genetic, biological component to homosexuality. Secondly, there is absolutely nothing unnatural about homosexuality. If at least 1500 species from humans down to worms practice it, there is no reason to believe it isn't natural . Only 3 percent of mammals are socially monogamous and literally none are completely sexually monogamous. Which is really unnatural?
http://www.nytimes.com/2005/05/09/science/09cnd-smell.html?ei=5065&en=bf437458d36709cf& ex=1116302400&partner=MYWAY&pagewanted=print