There is definitely evidence on both sides of the table. Due to a lack of scientifically conducted experiments, I fear that the only sources I can cite are somewhat unreliable.
However, irregardless, "Homosexuality is not a mental disorder and the APA opposes all portrayals of lesbian, gay and bisexual people as mentally ill and in need of treatment due to their sexual orientation." -
source
Source
This article actually supports Schroeder's theory. It basically refutes all of the arguments in favor of a genetic reason for homosexuality. But it does so by knit-picking existing studies on the topic. No where do they actually conduct their own experiments. In my opinion, their criticism is is at best poorly done. This article is comparable to a court hearing where there is plenty of circumstantial evidence, but because there is no convicting evidence the defendent (people against genetic causes of homosexuality) win the case.
For the record, I do not like homosexual people. This may sound hypocritical, but it is often times not because of their sexual orientation. It is because of their ridiculous ideas, and how they act as if they are martyrs. They claim to want accpetance, but they go out of their way to prove how different they are. If something even slighty offends them, they fucking go picketing. They intentionally blow things out of proportion, which is fucking idiotic. In short, they remind me of a bunch of 5th graders crying to the recess teacher about how some kid called them a butthead. If homosexual people want respect, then they need to stop acting so damn facist.