The ruling generation names of Maina and Mwangi are also very popular male Gĩkũyũ names. The theory is also that "Waciira" is also derived from "ciira" (case), which is also a very popular masculine name among the Agĩkũyũ. This would call into question, when it was exactly that children started being named after the parents of one's parents. Had that system, of naming one's children after one's parents been there from the beginning, there would be very few male names in circulation. This is however not the case, as there are very many Gĩkũyũ male names. One theory is that the female names are much less, with the names of the full-nine daughters of Mũmbi being most prevalent.