Historically most people didn't move all that much. So you can still see this in many non-western countries. Your cousins live in your community, your parents see their brothers and sisters very often, and this forms a support structure.

My theory is this accounts for why mental illness is so rampant in Western countries, but comes nowhere close in more community oriented cultures. Tribe, is an outstanding book on this topic. We aren't meant to be a bunch of autonomous units competing against each other.