[yongjik]

Eh, I've seen my baby sucking on its thumb, and then the baby jerks and the thumb goes away, baby cries, somehow the wild flailing gets the thumb back to the mouth. Baby happy again, sucking on its own thumb.

I agree that we are not born a blank slate, but at the same time, there's a lot of knowledge missing on a newborn baby.

[esperent]

Even if the baby has trouble getting the thumb into the mouth at first, it has no trouble sucking it. Or any of thousands of other instinctive behaviors.

[dkersten]

Yep, the baby knows how to cry when not sucking it’s thumb for example, and not cry when its content.