How are the Greasers gang like family to each other?

In the book "The Outsiders" the Greasers all know what it is like to be the outside group looking inward.  They all have economic hardships, few own vehicles, and they have dysfunctional families.  They also have a common enemy, the Socs.  They are the kids who nobody seems to want or care about what happens to them.  Pony Boy, Dally, and Soda Pop have each other and are a real family, but even they have lost their parents who died in a car accident.  The boys provide each other with support, friendship, someone to get each other's back, a kind word as well as joking and laughter, and acceptance.  In their homes many of them do not feel loved or have people who are concerned about them.  However, among each other they are one and a part of them feels fulfilled where the gap of a family is lacking.