People usually can NOT help being unloving, rigid, narcissistic, or egocentric because they learned it long ago, and slowly. It’s ingrained.
I do not think you can get very far in thinking that way. He was what he was...no matter if it was genetic, chemically biological, brought on by trauma, or abuse in his own childhood. It is what it is. You either accept that or not. You accept him or do not accept him. It is good to explore the reasons behind him, but it does not always give closure in the way you think.
We all as we age, look back at how we should have, or could have done things differently. The concepts eluded us at the time (I am soon to be 62). Your father wrote a book, and looked back on his life. He could not have changed back then.
It doesn’t matter if he chose to or was unable to. This part one has to accept, when dealing with childhood traumas and abuse. Both of my parents did the best they could. It’s was mom who abused us kids. She was mentally ill and came from child abuse too. My dad was abuse, was an unwanted orphan at age 7, lived in an orphanage with strict authoritarian nuns. He had no training on how to love, parent, communicate, or nurture us kids. So it guess he could not help it either, but for things said, and how he did not deal with problems in our home, and allowed our mom to physically and mentally abuse us...I will not forgive him. I finally forgave mom around 5 years ago.