Lol another thing i'm nerdy about, well it depends on the culture's definition of these feelings(the gut feeling) really...the terms change according to the cultural lens you see these from..
There's a lot of speculation, but i have just been reading about developing your psychic abilities to be more receptive.. Just like SRD420 said she can sense negative vibes that pertain to sexually perverted individuals, well that shows that she has developed her ability to be receptive to a certain energy. There is a theory in eastern culture(well hindu/traditional indian culture that i know of) that the pineal gland, is actually the the physical organ that is essentially your 6th sense. This is goes from an interesting theory in one culture that can be seen in many other religions, where the head is considered sacred/special.
i do believe in this "6 sense" and i believe its just as important as other senses that we know of, such as taste, smell, sight ....yada yada...but our culture(american culture) doesn't really dwell on it, and especially with the influence that modern medicine and 'scientific' explanations overrule traditional explanations. The most accepted explanation of a gut feeling derives from the psychological study of instincts, like mothers with their children, but i think this is just a cop out for all those events that cannot be described with 'instincts' or genetic makeup of certain individuals...
Pineal Gland:
known by some cultures to house the 6th sense that is able to send and receive messages through non-verbal means
For example, in Santeria(Ifa), you lay on the ground(or kneel depending on your status) and put your forehead and face on the ground and put the top of your head towards the drums that house the Orisha's.
In Buddhist cultures as well, believe that the head is the most sacred and violating that area(by patting the head or any other physical contact ) is not respectful.
Thats just the beginning ofmy explanation..lol