Frank absolutely detests his father. Throughout the series Frank tells the audience of this fact (while everyone else thinks he's a dutiful son who loved his father). We know that Frank grew up poor and his father was an unsuccessful peach farmer. Frank hated the confines of his poor small town upbringing, and a lot of that resentment was focused on his father. Frank described his father as a coward with a weak personality and a drunk. A major point that illustrates this is the time that Frank's father tried to commit suicide by shooting himself in the mouth, but couldn't pull the trigger, so he asked Frank to do it for him. Frank regrets that he didn't do it, and lived the rest of his life hating his father's lack of courage and constant abuse.
In his letter to President Walker in episode 13 of season 2, Frank wrote:
I want to tell you something I have never told anyone. When I was 13 I walked in on my father in the barn. There was a shotgun in his mouth. He waved me over, 'come here, Francis,' he said, 'pull the trigger for me.' Because he didn't have the courage to do it himself. I said 'no, pap' and walked out, knowing he would never find that courage.
The next 7 years were hell for my father but even more hell for my mother and me. He made all of us miserable; drinking, despair, violence... My only regret in life is that I didn't pull that trigger. He would've been better off in the grave and we would have been better off without him.
