My anecdata confirms this, one of my three is not a nip-head.
>Most cats, that is. 50-70% do not respond to catnip.
Wouldn't that be the opposite of "most"?
I suspect like most things in nature it's a bell curve; of varying responses. My cat responds, but not super enthusiastically. I've had other cats that just ignored. And other cats that went crazy for the stuff.