Implied Premise: Sexual orientation (further implied homosexual behavior) is a trait you are born with, like hair color...
Counter argument: Fact: Heterosexually oriented adults exist who choose for religious reasons to be celibate. Obviously, adults have the power to choose to be celibate. Therefore, sexual orientation is irrelevant to the choice to engage in sexual activity whether it is heterosexual or homosexual. In other words, regardless of whether or not someone is “BORN homosexual” (a point which I do not grant), their voluntary choices determine their behavior (i.e., “being celibate, or not).
But: Virtually ALL phentypes (observable characters of humans or other organisms) are ultimately the product of an interaction between genes and environment. In some cases, an environmental component may be minor, in others genetics may be minor. This a problem when scientist (in the interests of simplicity) calls a gene the "gene for X". What a gene for X really corresponds to is a gene that has at least alleles (forms) that shows a detectable impact upon a phenotype when that one of those forms is present in one (for dominant phenotypes) or two (for recessive phenotypes) copies.
Personally, I find some of Hamer's work on genetics and faith to be poorly supported, though I have only scanned his book. His "gay gene" work seemed reasonably solid. I read the original paper when it came out and it was a solid linkage study, though those sorts of studies only localize variant forms of a gene to a large section of a chromosome, potentially including multiple genes that contribute to a phenotype.
Science may not have all the answers, but if given the chance, it could at least inform these debates.
I didn't see anyting in your counter-arguments that actually took issue with the statement above, which I find perfectly reasonable. By definintion science can't have ALL of the answers. But anybody who igornes it completely is not connected to reality. Before jumping on my case, note that all I'm saying is science should never be ignored completely - how much weight it should be given relative to other considerations is an open matter that I think we all expect to see different folks having different opinions on.
Regarding the other arguments:
1. Homosexual individuals are only incapable of reproduction if they are exclusively homosexual. That is not the case and was probably even less the case during periods of history where men were expected for social reasons to marry and carry on the bloodline. Even in America, many gay men probably married during the '50 simply because being gay was not acceptable.
2. There are two reasons why a gay gene would persist in a population:
a. mutation-selection balance - the removal of genes from the population is balanced by novel mutant alleles. For reasons I won't go into, this typically involves the generation of recessive alleles of a (physically) large gene. This is unlikely to be the explanation, since it cannot explain the large proportion of homosexuals in the population unless different assumption are made.
b. sexually-antagonistic genes - genes that increase the fitness of one sex while reducing the fitness of the other are very well characterized (think of the train in peafowl - peahens definitely select males on the basis of their train, but it increases the impact of predation on peacocks). In the case of a gene for male homosexuality the allele conferring a homosexual phenotype would have to have a DIFFERENT phenotype in females. I think a study in Proc Roy Soc London (a scientific journal) provided evidence for this that was suggestive but not conclusive (my memory could be fading me - I remember this from scanning abstracts). I suspect this is the case.
I would add that both of these compatible with evolutionary theory, and the existence of sexually-antagonistic genes has been hypothesized to have a specific impact on the evolution of sex chromosomes. Genome projects have confirmed those predictions - mammalian sex chromosomes look the way you would predict from theory, and completion of the chicken sex chromosomes should provide a second test.
I would read something more recent than Skinner, who died 15 years ago. Off the top of my head, I know Joan Roughgarden has a popular book, though she does have the potential for an agenda. But there is a bigger problem: the naturalistic fallacy - does the way things ARE determine how they SHOULD be? I would say no. Imagine if somebody invented a drug that doubled our lifespan (and kept up healty - so we could live to 150 years of age and be able to work and enjoy ourselve for most of that). That is not natural! But how many would say it was evil because it is not natural? (a few would, but I suspect most of us would be lining up for the shot)
So, even if all of your facts were absolutely correct, that would simply say how things are, not how they SHOULD BE. Likewise, if half the population were born with a homosexual orientation, it would be exactly the same.
I support full gay rights for a philosophical reason - that of equal treatment. I am straight but I really don't CARE if somebody else is gay. Being promiscuous is probably a bad idea whether you are straight or gay, and if you are promiscuous you should always use condoms with strangers. But that is a PUBLIC HEALTH issue. It doesn't address the big issue of whether folks should have the right to do what they want sexually, as long as only adults are involved and everybody has given consent.
Ultimately, EVERYTHING is (potentially) subject to legal prohibition. The question is, what is wise for the government to prohibit. Even if I personally supported sodomy laws (which I don't) I would much rather have the cops out catching folks who assualt, rob, rape, etc. than having them catch folks engagin' in sodomy (assuming they are doin' the sodomy behind closed doors).