Before I start, I just want to clarify a couple of things. First, any hatred or violence toward LGBT (which has been misnomered as homophobia) is completely wrong and I vehemently oppose any physical or emotional harm done toward LGBT people (or anyone for that matter). Second, NO ONE has ever CHOSEN to have same-sex attractions. However, this does NOT mean that if something was not a choice then it must be inborn. Let me explain myself.
There have been several studies on the relationship on the possible biological influences on the development of human sexuality. Surprisingly the very biased and not considered scholarly Wikipedia is quite accurate in their discussion of this topic (here). Let me quickly summarize three important studies.
1) In 1991, Bailey and Pillard did a study of gay brothers and found that 52% of identical twins were both gay and 22% of fraternal twins were both gay. In 2000, Bailey, Dunne and Martin attempted to repeat the test in Australia only to find that 30% of identical twins were both gay. Although these studies clearly show that there is a genetic component to sexuality, it also clearly shows that sexuality IS NOT ONLY LINKED TO GENETICS. Because if sexuality was purely a genetic trait, then 100% of identical twins would both be gay. In addition, the applicant pool was mostly advertised via gay magazines - slightly biased! Also a study by Bearman and Bruckner in 2002 shows that only 6.7% of identical twins were both gay, 7.2% of fraternal twins were both gay and 5.5% of full siblings were both gay. Even the American Academy of Pediatrics and the American Psychological Association both state that sexuality most likely is a combination of biology and environment! When will the gay community, society and media read up on facts and science!
2) Simon LeVay also did a study released in 1991 on the hypothalamus. He examined 41 cadavers (which evokes fond memories of my two full semesters of Gross Anatomy lab and Head & Neck Anatomy lab while in Dental School!) - which he classified as follows: 19 gay men who had died of AIDS, 16 presumed heterosexual men (6 of whom had died of AIDS), and 6 presumed heterosexual women (1 of whom had died of AIDS). He found a portion of the hypothalamus, the INAH3 group to be twice as big in the heterosexual male group as in the gay male group. But there were also some conflicting results as well. LeVay himself concluded, "It's important to stress what I didn't find. I did not prove that homosexuality is genetic, or find a genetic cause for being gay. I didn't show that gay men are born that way, the most common mistake people make in interpreting my work. Nor did I locate a gay center in the brain...Since I look at adult brains, we don't know if the differences I found were there at birth or if they appeared later." Need anymore be said?
3) Dean Hamer in 1993 did a chromosomal study on gay brothers and found a shared marker on the X chromosome at Xq28. Unfortunately, this was dubbed by pop-culture as having found the "gay gene." Hamer himself (who was gay) even said, "...environmental factors play a role. There is not a single master gene that makes people gay...I don't think we will ever be able to predict who will be gay." In addition, other scientists tried to replicate the results but were not able to find this common shared marker among gay brothers. But most damaging for Hamer was the fact that he did not have a control group of non-gay subjects. If the control group had the same shared marker on the X chromosome at Xq28 as the gay brothers, then this finding would be COMPLETELY INSIGNIFICANT.
So as of yet, there is NO evidence that people are born gay and there is NO evidence of a gay gene!
To make matters even more difficult, it is difficult to empirically and scientifically classify and determine homosexuality. If any of you know one, please let me know. There is no blood test, radiograph, MRI, etc. to determine whether someone is gay or straight for that matter. The ONLY way that people know whether one is gay is if this one makes a SELF DECLARATION. That is the only way. And by definition, this is not objective (or scientific) but rather subjective.
With all of this said, I believe that the Church must have compassion for LGBT people. Christians must shower them with the love of Christ so that they would come into a relationship with Jesus Christ who will redeem and transform them. Jesus was perfect in justice and love as He came to point out our sin but also to save us from our sin by dying on the Cross for us all! I pray that Christians live out that example of justice and love!