"COMMON KNOWLEDGE" MUSINGS

COMMON KNOWLEDGE MUSING "Common knowledge" is not so common as it sounds or seems. Which knowledge is referred to? Is it that "common," intuitive, knowledge that is mysteriously embedded in the neural and cellular morphology of mankind prior to birth; that is genomically, culturally, epigenetically recycled into embryos, being the naturally selected byproduct of all prior generations' ontology? Or is "common knowledge" that body of acquired, codified information that is shared among certain nations, as man's common heritage? Included within this broad category would be mathematics, music, science, dance, art, farming, medicine, technology and many others? Which knowledge is "common" and which is uncommon ? Otherwise stated, which brand of common knowledge does the idiom refer to? Both?