Dean Heilman Hamer (born May 29, 1951) is an American geneticist, filmmaker, and author. He has made several sensationalistic claims about finding single genes that cause various traits like being gay or religious.
Hamer has made several films about sex and gender minorities, including Out in the Silence, Kumu Hina, Leitis in Waiting, and Kapaemahu.
The archival information below will be updated in the future.
Though most scientists hypothesized that sexual orientation is a polygenetic trait that is also affected by environment, Hamer made a lot of news by claiming to have discovered the “gay gene” in the early 1990s, which Northwestern University psychologist J. Michael Bailey and friends are trying to replicate, notably Khytam Dawood.
For the best overview of Hamer’s work, please see American Eugenics: Race, Queer Anatomy, and the Science of Nationalism by Nancy Ordover. Pages 57-124 deaal exrensively with Hamer’s causation theories tie in with eugenic ideologies.
Following his “Xq28 theory” of gay DNA, Hamer has switched gears and now claims to have discovered a “God gene.”
This claim prompted John Horgan to wonder aloud in a review, “Given the track record of behavioral geneticists in general, and Dean Hamer in particular, why does anyone still take their claims seriously?” 
Having recently read a completely uncritical profile  of Dean Hamer and his new book on the alleged “God gene,”  I have been thinking a lot about how fringe scientists are able to manipulate the media and get publicity by making especially dramatic claims. I have also been watching how skillfully the evolutionary psychology crowd manipulates peer-review (as in other evolutionary psychology peers) to get in the mainstream press. Their conclusions typically bolster what laypeople already believe to be true or claim something that has not been independently verified.
Columbia Journalism Review has just published an interesting piece on the ways journalists can end up giving disproportionate coverage to fringe scientific views in the name of newsworthiness or balance.  They take three examples:
1. LA Times reporter Scott Gold got dressed down for “bias” in a piece about the discredited link between abortion and breast cancer, because he questioned the scientific credentials of the lone dissenter.
2. The media’s gullible coverage of Clonaid’s bogus announcement about the first human clone.
3. How global warming coverage is manipulated by scientific dissenters funded by energy companies.
We have seen all three journalistic errors happen in the BBL/Clarke media coverage. From the Columbia article:
None of those examples of poorly “balanced” science reporting arise from precisely the same set of journalistic shortcomings. In Scott Gold’s case at the Los Angeles Times, he appears to have known the scientific issues perfectly well. That gave his writing an authority that set off warning bells in an editor wary of bias. That’s very different from the Clonaid example, where sheer credulousness among members of the media — combined with sensationalism and a slow news period — were the problem. And that’s different still from the problem of false balance in the media coverage of climate change in the U.S., which has been chronic for more than a decade.
Yet in each case, the basic journalistic remedy would probably be the same. As a general rule, journalists should treat fringe scientific claims with considerable skepticism, and find out what major peer-reviewed papers or assessments have to say about them. Moreover, they should adhere to the principle that the more outlandish or dramatic the claim, the more skepticism it warrants. The Los Angeles Times’s [editor] Carroll observes that “every good journalist has a bit of a contrarian in his soul,” but it is precisely this impulse that can lead reporters astray. The fact is, nonscientist journalists can all too easily fall for scientific-sounding claims that they can’t adequately evaluate on their own.
That last sentence is the most astute summation I’ve read describing what we are up against. These guys essentially traffic in confirmation bias and oversimplification. Responsible scientists stick to data when discussing complexities of this nature.
Let’s take as further examples J. Michael Bailey and Joan Roughgarden. I consider Bailey similar to Hamer (in fact, they have collaborated): both claim to have “discovered” a genetic basis for homosexuality, and both received considerable publicity for their announcements. Follow-up by the mainstream press was negligible, especially in the case of Hamer’s still-unreplicated work. I think both got a taste for the spotlight and continue to try to find their way back into it with a lot of unsupported conjecture and tendentious arguments. 
This is in apposition to Joan Roughgarden’s book , which also received generally favorable press in the mainstream media. The difference as I see it between the Bailey/Hamer crowd and Roughgarden is that Roughgarden positions her work as a hypothesis based on extensive research and a comprehensive array of data points. Bailey, Hamer, Levay, and like-minded folks prefer to do the opposite: extrapolate based on one data point, a problem that also happens in lay discussions about etiology of gender identity. One scientific-sounding sound bite become the rickety soapbox from which grand pronouncements are made: Xq28, VMAT2, INAH-3, BSTc, etc.
Taking this one step further, Bailey-Hamer types like to attach a media-friendly meme to the fancy acronym: gay gene, god gene, selfish gene, brain sex, what have you. This forces more responsible scientists to respond in kind, dumbing down the discourse for the lay press, simply to compete. The tactics used by Bailey/Hamer etc. are reminiscent of the direction most debating in this country is heading: George Bush can sway laypeople with this kind of simplistic discourse, while people like Gore or Kerry find themselves trying to explain the nuance and complexity of geopolitical reality in a world that expects everything explained in black and white.
I find it especially interesting that much of the criticism of Joan’s book claims it is “politically correct.” This is of course a now-classic rhetorical move used by those who wish to dismiss the evolution of ideas and definitions. Luckily, it’s the sound bite of last resort for the pseudoscientist, and usually is a sign that they are losing the argument to the progressive and responsible scientists.
In a 2004 article, this self-proclaimed “cynical old queen” stated:
“The interesting thing about cultural stuff is that it is not necessarily stuff that is good for people; it’s just good for the culture or the organization that creates it. Which gets into the people who profit from it, who are priests and bureaucrats.” 
Though Hamer was talking about religion here, his comment also applies to science and the organizations which claim to adhere to science. In fact, Hamer continues to profit from his adventures in pseudoscience, both as a priest selling his belief system (and poorly researched books) and as a well-paid bureaucrat with the US government.
1. Hogan J. Do our genes influence behavior? Why we want to think they do. Chronicle of Higher Education. 26 November 2004 Volume 51, Issue 14, Page B12
2. Roehr B (2004). Nature vs. nurture: “Gay” gene pioneer tackles God. Philadelphia Gay News. 1 October, page 1.
3. Hamer D (2004). The God Gene : How Faith is Hardwired into our Genes. Doubleday.
4. Mooney C (2004). Blinded by Science: How ‘Balanced’ Coverage Lets the Scientific Fringe Hijack Reality. (6) November/December.
5. e.g. Bailey JM (2003). Man Who Would Be Queen.
6. Roughgarden J (2004). Evolution’s Rainbow.
7. Roehr B (2004). Nature vs. nurture: “Gay” gene pioneer tackles God. Philadelphia Gay News. 1 October, page 1.