I've enjoyed a bisexual nature all my life. I've had a navel fetish since pre-adolescence and discovery of erogenous wiring in my own body. It either is or isn't erotically sensitive; for those with a dead zone in their umbilical scar, there's no use trying to explain it. Probably about half of humanity have erogenous navels. When it is a sensual spot, it tends to be a singularly powerful one, and since mostly men have seen fit to stimulate it, I've associated it with the masked twin within me.
I've long stopped listening to self-certified experts try to explain male bisexuality, or this or any fetish, with analysis sourced by their own creepy signposts. Our cultural denial of male bisexuality is political commandment, not scientific fact. It is what it is, and doesn't maim or kill any one or thing; it leaves no heavy carbon footprint, although I'm sure dedicated tree-huggers can find one. Like its abysmal mix with art and justice, politics should have only limited connection to sexuality, so, of course, we make it an inescapable one.
It should be no one's business but one's own.
Location
North Hollywood, CA