I have 9 cats and some knead and some don't. The ones that knead seem to be the ones that we got young (less than mos). I think it might be because they lost their mother too soon. I have also read that somewhere. One cat was left on our front porch, about 3 mos. old and very sick. He is 4 now, and will get on the blanket my husband puts on his lap and will suck and knead.