covering of mouth or covering eyes when something that the viewer see and relates to that is somehow not fully acceptable in society. Sort of preventing of saying or seeing something.

I think you will find one or other of these gestures is so common, and though learned, has meaning to the "doer" that is comforting at a level that is definitely nature (cf nurture)

FWIW I have 2 books on body language, which I thought might help with job hunting years ago.