A Principle We Should Keep

"Blood makes you related, loyalty makes you family." This fundamental truth is what keeps families together to this day. Sure, blood may bind you to one another, but love and loyalty are what keeps a family together. And sometimes, blood ties are not even a factor. I know there are people in this world I love like family that are not related to me by blood. This is one of the most important principles in our world today. Without this, there would be no close family relationships, no wonderful groups of friends, no ties that are so awesome that you would die for one another. 
So what would we do if the world fell down around us, if life as we know it ended? Could this principle survive? I feel that it should. Family loyalty is what kept the father and son together in The Road and a lack of which killed the mother. How many people would have survived if their family (be it blood or friends) didn't turn on them, or chose to fend for themselves, but instead banded together and helped each other? And not like the gangs in the book, but instead a larger version of the father and son, protecting each other, feeding each other, and doing whatever they could to ensure that all survived. 
This principle is also what helps make people who they are. Your family defines you (again, not just blood but friends). If the bad guys, the cannibals, had kept their family, would they still eat the flesh of their own? I don't think so. The disapproval of your family is oftentimes enough to keep you from doing something, especially something you're already nervous, already unsure about, like cannibalism. 
When the world falls apart, family loyalty will help people to keep it together.