Ticklish feet

My oldest cousin is in her 30’s and has EXTREMELY ticklish feet, I on the other hand do not, neither do my siblings or even her parents.
My question is: What makes feet so ticklish?

Thanks. :wink:

I’ve heard that ticklishness is a defence mechanism to protect vulnerable parts of the body.
This would explain ticklish armpits, where the body is very soft, with many vital organs nearby.
Dunno how this would translate to feet, though…
I’m sure others will be around to give you a more useful answer…