One thing I've also noticed is that the adult Fredo and his mother never have a scene together except when she is dead! The only hint we have to their relationship is when Fredo tells Michael that she'd told him he'd been left by gypsies. God knows, that must have further deepened his insecurity as the middle son. And does anyone think that the pneumonia he suffered as an infant contributed to his mental "slowness"? I mean, he was attended by some neighborhood woman who was using some old country methods on him. Who knows if it really was pneumonia? She was no dcotor!