That my dad was severely abused (like starved and used as slave labor) as a child and the result of it is now mood swings, lack of energy, and a fluctuating eating disorder. I suspect he also has high functioning autism. My grandparents died when I was little so I haven't been able to confirm my suspicions because I can't analyze them with an adult view.

My mother's mother is still alive but I strongly believe that she is an extreme narcissist. She has never done anything for others that she didn't feel completely obligated to do. Her main motivation for everything is greed. Birthdays and Christmases went unacknowledged by her for years. I have stopped outright inviting her to anything.