In Harnessing human nature Part I, we saw how natural selection takes place not only on the individual level, but on the group level. No man is an island. We are who we identify with, we make alliances, good and bad. The high point of any civilization is when its state, warrior groups conquer others, loot and occupy, and build monuments to glorify it all. In rare exception to this, sometimes civilizations just coast along under wise leadership. Andalusia under Muslim rule from the 8th to 15th cc was probably humanity's high point, though it came to a typically nasty end with the reconquista.
But what about the family? What role does it play in civilization, in shaping individuals, before they move on to their adult groups?