In chapter 7 of Things Fall Apart, Okonkwo kills Ikemefuna. Ikemefuna was given to Okonkwo's village to be sacrificed. Sacrificing ikemefuna would prevent war between these two neighboring clans.
For three years, Ikemefuna lives in Okonkwo's household. Ikemefuna has become part of the family. Okonkwo amd Ikemefuna love one another as father and son. Because of the traditions of the Ibo Society, Okonkwo has to witness and even participate in the killing of Ikemefuna. Okonkwo is afraid of being thought of as weak; therefore, he cuts ikemefuna down with his machete.
Okonkwo's son, Nwoye, is extremely troubled by such a tradition as the killing of Ikemefuna. Nwoye cannot understand how his clan could be so cold.
While it is perfectly accepting to kill Ikemefuna, the accidental killing of Ezeudu's son is another story. In chapter 13, Okonkwo accidentally shoots Ezeudu's son during a funeral service. Okonkwo's gun accidentally fires. Nonetheless, Okonkwo has to pay a severe penalty for accidentally killing Ezeudu's son. He is banished from his clan. He has to uproot his family and move to his mother's homeland:
It is a crime against the Earth goddess to kill a clansman. There are two types of crimes, male and female. Okonkwo has committed a female crime because the murder is an accident. Nevertheless, he is forced to flee from the clan. He may return after seven years.
Again, the traditions of the Ibo are strange. It is Okonkwo's duty to kill the innocent boy Ikemefuna, but he is cursed when he accidentally kills one of his own tribesmen. It makes no sense to Nwoye, and the nature of justice in Ibo society will likewise seem skewed to readers of the novel.