mine is psychological, brought on by the thought of being with a controlling woman. doesn’t show up for hours so if I talk myself out of it I’m ok. Self-cognitive therapy.
A quite agree that there is tremendous variation between people.
However, on the subject of IBS, have you tried a half teaspoon of peppermint extract in a glass of water twice daily? I’ve known several diagnosed IBS sufferers who have experienced extended relief with that.
Recently, a scientific study validated what had long been suspected anecdotally.
http://www.adelaide.edu.au/news/news44321.html