So what happened to those countries that eat bugs nevertheless? They're going against their instinct?

Or maybe it just is cultural, but in your culture it doesn't seem that way.

With the right conditioning, people can be made to accept all manner of madness.

The rejection of things can be "madness" too.

We know that plenty of "natural" phobias are actually cultural, i.e. learned behavior. Toddlers and even infants pick up on social cues and develop fear and disgust responses by mimicking the behavior of adults and older children.

"Conditioning" is an unnecessarily spooky framing for what is quintessentially "culture".

My toddler's first reaction to ground pepper was to cry out in pain, exclaim "hot!" and never want to go near it again. Would you call it "conditioning" if my child later in life develops a taste for peppery dishes?

Some aversions are cultural, others aren't. Which are which?

The fact that bug eating remains niche around the world, generally only seen in regions with a recent history of food insecurity, suggests that the conditioned madness is eating bugs, not aversion to bugs.

I don't believe we have any such instinct, we only have cultural norms.

I can't imagine any ethical experiment which would adequately separate the two factors. It's difficult to raise a child without influence of their surrounding culture.

Predators in the wild tend to eat the vital organs of their prey first, yet for a great many people eating organ meats is gross.