According to jomo kenyatta , why is having many children important in gikuyu society

According to Jomo Kenyatta, having many children was important in the Gikuyu society because

The Gikuyu people believed that their ancestors reincarnate again in the form of their children.  Jomo Kenyatta, a Gikuyu by identity, served as the first prime minister of Kenya.

He was kind of conservative and possessed an inclination towards the culture. He himself had eight children. He too believed in the belief of his culture which said the ancestors are reborn as children in the same communities and families.

it affected it because the kingdoms (with trade) slowly got richer and richer.