My grandfather, whom I never knew, died when my father was only 3 y/o. So, you can easily say my father never knew my grandfather either. He was an alcoholic.
Alex
"There is a cult of ignorance in the United States, and there has always been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that "my ignorance is just as good as your knowledge."
-- Isaac Asimov