In school, many classes, generations were always said to be twenty years. Did a search, see the first paragraph of: https://en.wikipedia.org/wiki/Generation h

In school, many classes, generations were always said to be twenty years. Did a search, see the first paragraph of: https://en.wikipedia.org/wiki/Generation https://en.wikipedia.org/wiki/Generation > It can also be described as, "the average period, generally considered to be about 20– 30 years, during which children are born and grow up, become adults, and begin to have children."