Proposal
According to this hypothesis, the God gene (VMAT2) is a physiological arrangement that produces the sensations associated, by some, with mystic experiences, including the presence of God or others, or more specifically spirituality as a state of mind (i.e. it does not encode or cause belief in God itself in spite of the "God gene" moniker).
Based on research by psychologist Robert Cloninger, this tendency toward spirituality is quantified by the self-transcendence scale, which is composed of three sub-sets: "self-forgetfulness" (as in the tendency to become totally absorbed in some activity, such as reading); "transpersonal identification" (a feeling of connectedness to a larger universe); and "mysticism" (an openness to believe things not literally provable, such as ESP). Cloninger suggests that taken together, these measurements are a reasonable way to quantify (make measurable) how spiritual someone is feeling.
The self-transcendence measure was shown to be heritable by classical twin studies conducted by Lindon Eaves and Nicholas Martin. Interestingly, these studies show that specific religious beliefs (such as belief in Jesus) have no genetic basis and are instead memes, that is cultural units transmitted by non genetic means, as by imitation.
In order to identify some of the specific genes involved in self-transcendence, Hamer analyzed DNA and personality score data from over 1000 individuals and identified one particular locus, VMAT2, with a significant correlation. VMAT2 codes for a vesicular monoamine transporter that plays a key role in regulating the levels of the brain chemicals serotonin, dopamine and norepinephrine. These monoamine transmitters are in turn postulated to play an important role in regulating the brain activities associated with mystic beliefs.
What evolutionary advantage this may convey, or what advantageous effect it is a side effect of, are questions that are yet to be fully explored. However, Dr. Hamer has hypothesized that self-transcendence makes people more optimistic, which makes them healthier and likely to have more children.
Read more about this topic: God Gene