Achebe is keen to present Okonkwo not as some idealised hero that can do no wrong, but as a real human being who faces many different kinds of conflicts and troubles in his life. Of course, one of the biggest conflicts that he has is his desperate desire to be the polar opposite from his father as possible. This leads him to adopt more masculine and manly behaviour even in situations when he feels in his heart of hearts that this isn't actually appropriate. In the same way, Achebe shows us plenty of examples of when the temper of Okonkwo gets the better of him. Consider the following example from chapter five during the New Yam Festival:
...when he called Ikemefuna to fetch his gun, the wife who had just been beaten murmured something about guns that never shot. Unfortunately for her, Okonkwo heard it and ran madly into his room for the loaded gun, ran out again and aimed at her as she clambered over the dwarf wall of the barn. He pressed the trigger and there was a loud report accompanied by the wail of his wives and children.
Fortunately, Okonkwo's ineptness with the gun means that nobody is hurt, but note how Achebe is focusing on Okonkwo's rage as a weakness and how this foreshadows his final tragedy. Okonkwo is presented as a character who cannot control his temper, and his actions whilst angry will shape the plot of this story.