Watch the video. The iguana just hatched and is already going on insane escape from snakes. That information has to be encoded there from the start. Thus without it would have been probably naturally selected out.

I agree it seems highly likely, I just can't make the leap to "has to be" when we know so little (if anything?) about how that would work.

Maybe I'm just being pedantic here, if so that wasn't my intent. I very much agree that anything being born seems to already known more than we give credit for, I just can't do absolute certainty there.