Today, he sounds like a combination of his grand mother and Katherine Hepburn.
It could be a genetic thing inherited from his grandmother.
Voices are definitely hereditary. My father and his two brothers sounded absolutely identical. Of their children I am the only one who has inherited the distinct Gladnick voice. I first realized this when I was 16 on the phone with an uncle from my mothers side and he shocked that I sounded exactly like my father. Before that I had the basic kid’s voice.
and/or, he’s smoked a log size doobie..