totally - but to be clear the question I have is more like "where in the body is this knowledge encoded (for lack of a better term)"

Do you have neurons in your brain that are pre-wired for these things? Is that encoded in your DNA? Like physically how is it inherited and the selective pressures applied?

Yes, yes, and you got it. Largely it’s DNA that controls development of neurons/muscles/etc. that mediate nursing, walking, and so on.

On selective pressures: human babies that aren’t born with the ability to nurse, or foals born without the ability to walk—because their in-utero development didn’t allow it—historically don’t survive, and thus don’t reproduce.

I think it's a chemical structure reacting to an energetic stimulus.