Re: Robert Hugh Follette, born approx. 1917, Pennsylvania
You do seem to have a tough situation there and he seems to be a shadowy figure. It's odd one of his other sons knew little about him. It is possible he used different names or went by Hugh at times. Ancestry shows there was a Robert H. living in Reading in 1993 who was born in May 1916.
He undoubtedly would have had a Social Security number and would have been the right age to have to register for the draft during WWII. But under what name?You might try the spelling of La Follette or Follett. He may have used aliases as well.
One possibility would be to find any one of his marriage records wherever they may be. It wouldn't have to be the marriage record with Grace. Any one of them might help you.
How did you determine his approximate year of birth? Any other clues about him?