When dealing with other people in any situation. Family or strangers alike, there are always only two options. Either you cooperate or defect. And the whole cacophony of the world is made by people either cooperating or defecting on each other.
However, it gets a little trickier than that. When you defect you gain an advantage a small one or a big one over others who are willing to cooperate. Most people are content in defecting in invisible and inconceivable ways to gain tiny benefits here and there and always not realizing the grand prize of cooperating. Because the grand prize is reserved always for people in honest and genuine cooperation.
And yet we may never know what grand prizes life has in store for us until we evolve the kind of minds which are strong enough to seek a grander version of things.