Some common surnames used by the Kalenji people of Kenya include Korir, Kirui and Chirchir, all of which are also first names, minus the prefix "Kip." Common last names among the Luo people of Kenya are also first names, and include Obiero, Obonyo and Ochieng.
Both Luo and Kalenji children adopt the "personal surnames" of their fathers as their last names. These personal surnames derive from the cultural practice of assigning children names based on the circumstances of their births preceded by a gender prefix. For instance, the Kalenji people use the prefix "Kip" for boys and "Che" or "Chep" for girls, while the Luo use the letter "O" for boys and "A" for girls. Thus, Kalenji parents name boys born at daybreak Kipkorir, because "korir" means "born shortly after dawn." When this boy has a child, his last name is Korir. Similarly, the Luo people name male children born in the late evening Othiambo; their offspring adopt the last name Othiambo or Athiambo.
Sometimes the Luo people also give children a Christian name when they are born. For example, parents might give a boy born at night the Christian name William followed by Otieno, which means "born at night." Traditionally, this boy's offspring inherit the last name Otieno or Atieno, but it is also acceptable for them to use his Christian name, William. Thus, his children could have the last names Otieno, Atieno or William. For this reason, it is not unusual for Kenyan siblings to have different last names.