Good news is rare these days, so I'd like to take a moment to celebrate last week's decision by a federal judge that Proposition 8, California's ban on same-sex marriage, is unconstitutional.

That's the news hook for my main topic: the misuse of my writings by religious fundamentalists. To my dismay, some Christians embraced The End of Science, which they misinterpreted as an endorsement of religious explanations of existence. When Christian radio talk show hosts had me on their programs, I had fun setting them straight. I told them that the only theology I find compelling is one in which God suffers from multiple personality disorder. (If you're curious, check out the epilogue of The End of Science, "The Terror of God.")

And speaking of setting straight, Christian homophobes have misused my writings on the biology of homosexuality, particularly "Gay Genes, Revisited," published in Scientific American in November 1995. In it I reported on weaknesses in the claims of scientists—and particularly the geneticist Dean Hamer, "discoverer" of the "gay gene"—that homosexuality has a genetic basis. (I've continued beating up on Hamer over the years for exaggerating the links between specific genes and behaviors; see for example this essay.)

Anti-gay Christians cite "Gay Genes, Revisited" to make the case that homosexuality is not hardwired; people with homosexual inclinations can change their behavior and even minds through therapeutic interventions. See, for example, the references to "Gay Genes, Revisited" on these Mormon and Catholic sites.

A few points: First, being a good tolerant liberal, of course I support gay rights—including the right to marry. Why shouldn't gay couples share the misery of us straights? Second, I can think of no dumber reason for doing or not doing something than what the Bible supposedly says. Third, I suspect that homosexuality is probably at least in part innate, even though the evidence so far is flimsy.

But I also see human sexuality as much too complicated, diverse and mutable to be explained in simple biological terms. Although some gay activists insist that a bisexual is really just a homosexual in denial, bisexuality is clearly a genuine phenomenon.

My views have been shaped by two of my best friends, whom I'll call Dick and Jane. They consider themselves bisexual. Each had been in both straight and gay relationships before they met and fell in love 20 years ago. They've been happily married now for 12 years, and everyone who knows them thinks they're a great match. This may sound sappy, but to my mind their love for each other as individuals transcends categories as crude as heterosexual, homosexual or bisexual.

I asked Jane and Dick—who are both computer scientists—to e-mail me their thoughts on the genetics of sexuality. Here are their responses, beginning with Jane's:

From Jane: It wouldn't surprise me if there was some biological basis for homo- or bi-sexuality. But I agree that the entirety of human sexual experience is probably too complex to be attributable to one physical factor. On one end of the spectrum, there's pure physical attraction; on the other end is the fullness of a long-term relationship. If biology plays a part, I imagine it's at the initial attraction phase. (What attracts me to a man or a woman? I'm not attracted to all men or all women. And the people I'm drawn to have very different qualities, so I can't really make a list. The attraction is just…there. I'm prepared to believe that it could be hardwired.) But after that, if you want to be in a relationship with the person, there's a lot of social, psychological and behavioral factors at play. If my relationship with Dick transcends labels, it's probably because it works for a bunch of different reasons. Yeah, there's the basic physical attraction (he's cute!), but he's also incredibly kind and smart and it turns out that we're super compatible. (There just aren't that many things about him that bug me and—incredibly—vice versa. But match either of us up with a different person and you could have a volatile reaction.) So we had some chemistry initially, and some luck. And years of getting along with someone who makes you happy makes you want to stay with them (and keep having sex with them!). Biological? Social? It really doesn't matter to me at all!

From Dick: The notion of a "gay gene" disturbs me in two unhappily familiar ways. First, it reinforces the common and simplistic notion that people belong to one of two "teams." Such thinking denies the experience of people like me and Jane and millions of others like us; it would be merely annoying if it weren't for the hurt it can cause. Bi teenagers feel pressure to choose sides, bi adults hear from gays that they're in denial, and much dialogue about sexuality is unnecessarily polarized. It's politically very convenient for gay activists, Christian fundamentalists and social conservatives to put everything in "us versus them" terms, but sexuality is much more fluid than that. Second, it is just one more tiresome example of genetic absolutism—not that scientists subscribe to this, but everyone else seems to. To deny that environment, upbringing, friendship or chance have any significant role in shaping an individual's development is simply pernicious. Granted, it's extremely likely that fully developed adults are unable to change their orientation (even despite the best efforts of those bigots who try to "convert" self-hating homosexuals), but this doesn't imply that the development itself was entirely predetermined. Again, though, it's very convenient for many people to pretend otherwise. I'm talking about the general population and the popular news media here. Naturally, researchers in the field have a much deeper and nuanced perspective, but subtlety and detail always get lost in transmission from experts to laymen. We're also dealing with a lot of prejudice, religious programming and scientific illiteracy. Personally, I can't believe that bisexuality is still an uncommon notion after all these years or that so many people think that everything is innate. It's not that ignorance of scientific facts is by itself evil. (How many of us can give the chemical composition of aspirin?) It's that, as John has shown above, it is wielded to bad ends. In the end, if it's not your area of research it shouldn't matter. It would seem elementary that how you treat people should not depend on their sexuality or where it came from.

Image: A march held in support of gay marriage, in San Francisco in 2004; courtesy of Wikimedia Commons