I believe that the best answer to this question would be a tragedy. However, there may be more than one genre that accomplishes this goal. A tragedy is, specifically, a form of drama. It, "treats in a serious and dignified style the sorrowful or terrible events encountered or caused by a heroic individual" (this is the definition given in Encyclopedia Britannica.) A tragedy most definitely depicts the flaws in human nature.
Page 6, is where Lennie talks about tending the rabbits in the book of mice and men.
Both of the fathers are violent and negative.
You don't want to have the past repeat itself so you learn about it to know its effect on the world.
