I'm not sure I believe this diagnosis. I think communications has made for more formal estrangement since it's pretty hard to find a lifestyle that explains why you can't video chat from anywhere anytime and the cost of even trans-continental travel is rarely a quarter of a year's salary.
The further you go back, the easier it was to have excuses to greatly limit contact and only have contact that is very impersonal. The average American is a decendant of adults who were never going to see their parents again. Most would have felt a great deal of social pressure to treat that as a hardship and disguise if it was their primary motivation.
I think hunter gatherers would have been predisposed to finding new groups at adolescence even if their culture lacked a specific rule for which sex does so, and the priorities of agricultural societies to keep land rights are probably not particularly compatible with our evolutionary past.
The further you go back, the easier it was to have excuses to greatly limit contact and only have contact that is very impersonal. The average American is a decendant of adults who were never going to see their parents again. Most would have felt a great deal of social pressure to treat that as a hardship and disguise if it was their primary motivation.
I think hunter gatherers would have been predisposed to finding new groups at adolescence even if their culture lacked a specific rule for which sex does so, and the priorities of agricultural societies to keep land rights are probably not particularly compatible with our evolutionary past.