I disagree with the last sentence in the question details. I don't think it is selfish at all to not have children. First, the world's population is at 7 billion now and still growing rapidly. This is highly unsustainable. read more
For the same reason it died out in Europe: As societies shift away from an agrarian economy, there's less incentive to have large families who can help work the fields. A large family is a much greater financial burden than a financial advantage in an industrial society. read more
In Vietnam when some family member is about to die everyone gathers around him/her. These are the moments of silence. The eldest son or daughter bends towards dying person to hear few last words. Then the eldest member of family suggests a name for the dying person. read more
Chinese culture traditionally favors big families where many generations of family members living under one roof. Traditionally, female children only move out when they're married and move to their husbands home. Male children usually “separate” the inherited properties after their parents passed. read more