So does that mean there is an atheist gene too? And what about people who are atheists and later in life become religious? Does this mean they underwent a genetic change? Inquiring minds want to know.
No, an athiest would be "lacking" the God gene.
Since the vast majority of people profess a belief in God, does that mean that people who do not are defective?
Of course it means that. It also throws out any idea of objective truth. If I believe in God because my genes force me to do so, and some scientist does not believe in God because his genes force him NOT to do so, then there's no way to question or change our conclusions; it's all a matter of "my genes" vs. "his genes." This scientist probably thinks that his so-called research is a positive step in the direction of tolerance and mutual understanding; it's not. It's a step in the direction of stifling any sort of rational debate on important issues.