I happen to think ticklishness is somewhat predictable. While this kind of physiognomy can be taken too far, I have no doubts about some of it.
We all have a combination of what are called fast-twitch and slow-twitch muscle fibers. Pro athletes and trainers target these differences strategically, depending on the sport:
https://www.acefitness.org/educatio...muscle-fiber-types-fast-twitch-vs-slow-twitch
I believe if we're observant, we can easily identify people with lots of fast-twitch muscularity by the way they move. The person who naturally tends to move quickly, with more jerks and twitches, will more likely be ticklish. The person who moves more slowly and fluidly will tend to be less ticklish.
Separately, and probably less predictive, I think there's an inverse correlation between body fat index and ticklishness, especially once we're talking about obesity. More skin and fat added to the same central nervous system, I believe, tends to result in less sensitivity. I'm
not saying someone with a little extra body fat can't be ticklish -- not saying that at all -- just that on average there's somewhat of a correlation of thinner people being more ticklish, in my experience.
To be clear: I can name my own particular examples of people who don't fit these generalizations. It's like saying "men to be to taller than women." But while existence of counter-examples do not a generalization disprove... if you disagree with the generalizations broadly, I'm happy to hear your thoughts.
🙂