I would argue it is due to nuclearisation of families, that has always accompanied industrialisation. See my other comment on this post https://news.ycombinator.com/item?id=48416228
Fascinating hypothesis. I wonder if technological and economic progress makes "nuclearisation" inevitable, i.e. people can just move wherever the best money is at.
Fascinating hypothesis. I wonder if technological and economic progress makes "nuclearisation" inevitable, i.e. people can just move wherever the best money is at.