All energy that is used up, lost, burned up, or evaporates, gets used in some other natural processes. And so if the universe is a zero-energy universe, where no energy can be created or destroyed, and all the energy that came into it still remains in it that means we are made of parts of the elements that formed the start of the universe:
And not only that, but if the first offspring came from the first man and woman that ever evolved, that also means that everyone you know, and everyone is history in related, or in other words, that asshole you hate, your postman, that prick who cut you off in traffic today, your boss, some kid playing soccer in a village in Mozambique, some random guy on his phone in downtown Warsaw, Poland, and most significantly for me, my girlfriend is my cousin.
So when you think of what distinguishes family from friends that feel like family, the line is suddenly gone. There is none. Though genetically more distant, your friends are still your family.