One of the main factors that promote the change from extended families to nuclear families is the greater employment and income opportunities we currently have. The possibility of employment for most members of a family, allows each member to leave their parents' house when they decide to form their own family, so it is not possible to form large families, since people have the financial conditions to bear the expenses of the family itself.
Another factor is the increasingly early independence that today's young people have, and it is common for young people to leave their parents 'homes early and form families away from their parents' homes.
