There is nothing in anyone's 201 files (that I know of) that references one's parents or grandparents.
@AARguy Not in a 201 file,that every clerk in the army has access to,but you might be surprised how much background is in your security file if you have a Top Secret or code name security clearance. The people that do those investigations ain't playing.
I somehow got hold of mine once,and was shocked to see so much stuff in there that I had forgotten about or hadn't thought about in years. It was a real eye-opener.
This,of course,was in the army of the 60's,where there were no or very few PC officers in line units.