Dean Hamer seemed to pour gasoline on the nature versus nurture debate over sexual orientation when he discovered “the gay gene” back in 1993. But the latest work by the NIH researcher might be even more incendiary. It’s out in a new book called The God Gene.

His earlier work didn’t identify a single gene responsible for making one gay, but rather a region of many genes on the X chromosome that correlates with an increased likelihood that males will be gay. Shortly thereafter, hip fags were sporting T-shirts that read “Thanks Mom for Xq28”, the genetic region that he had identified.

Personality traits – from sexual orientation to smoking – are the result of a complex interplay of multiple genes and the environment, a back and forth that begins in the womb and continues throughout life, Hamer explained.

This time around, the “God gene” really is a single gene: VMAT2. It makes a protein that transports monoamines, a chemical in the brain. A single variation in the gene affects people’s consciousness or the way they perceive the world, and Hamer has linked that to spirituality.

“All of the spiritual people, all of the great spiritual experiences, involved seeing reality in a fundamentally different way,” he said. “For a lot of people, that is tantamount to nuttiness, or schizophrenia, or something like that, but it’s a very intimate part of spirituality. With Paul [on the road to Tarsus in the Bible], obviously that was a very dramatic instance of that. Or when Mohammed went flying around in his dreams. But I think that it plays a role in people’s everyday life too. Just sitting at the beach, looking at the waves, people can have spiritual experiences and it’s because all of a sudden you just see the world in a little bit different light. I think that’s pretty cool. Everything is not as it normally appears.”

Hamer explained: “Spirituality is measured by something called the self-transcendence aspect of personality,” a category created by psychologists “that looks at things like, to what degree do people identify with the whole world around them, compared to just themselves. And to what degree do people feel that everything in the universe is connected by some sort of spiritual force.” It is different from other personality traits, he said.

When Hamer compared people’s behavioral and personality surveys with their DNA, a variation of the VMAT2 gene popped out as having a strong correlation. “It’s interesting, not because it is THE gene that makes people believers or not, but because just finding that one gene, we think, tells us something about the whole brain biochemistry of spirituality,” he said.

He says that VMAT2 is but one of what may well be hundreds of genes that play a role in spirituality.

Hamer carefully distinguishes between religion and the biological aspect of spirituality: “Religion is a cultural phenomena where the rules are made up by man or come down from God, depending on your point of view, but they are things that you learn, things that can be changed culturally. 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. I’ve always been interested in applying a scientific analysis to things that are really fundamental about people, like whether they are gay or straight, or whether they are spiritual or not.”

The field of behavioral genetics is a controversial one and Hamer has not shied away from that controversy, though he said his scientific colleagues have been leery of it. “They felt that way about sexual orientation and they feel 10 times stronger about this,” he said, adding that one of his bosses went so far as to suggest that Hamer wait until after he retired to write about the God gene.

Hamer’s work on the gay gene made him an anathema to the religious right. He doesn’t think that the God gene will have the same effect.

“I don’t see our findings as being anti-religious or pro-religious at all. If you believe in religion, then you will look at the research and say it establishes the truth that God gave us a specific mechanism for believing in religion; it’s not just an afterthought, it’s hard-wired into our brains. But of course, if you are anti-religious you can look at it another way and say, ‘Well this proves that religion isn’t really coming from above, it’s coming from inside.’”