Hannah Okonkwo is Obi's mother. She is obedient to her husband Isaac's decree that they forsake certain Igbo traditions because of their Christian beliefs. But it is also clear that Hannah still respects Igbo culture and many traditions. There is a telling moment in the text when the narrator describes how the European custom of cutting the cake at a wedding had been reinterpreted in Igbo culture. The idea was that the person who cuts the cake first will be the senior partner. The day that Isaac and Hannah were married, Hannah cut the cake first.
Though Hannah and Isaac keep their children from most parts of Igbo culture, Hannah was willing to secretly break her husband's decree when she realized that Obi was suffering at school because he had no knowledge of Igbo folk tales. We see further evidence of Hannah's adherence to certain cultural customs the day she calls Obi to her bedside and explains that if he marries Clara, she will kill herself. This is Obi's last interaction with Hannah. She dies shortly thereafter.