What does your family mean to you? How important is it for you?
To me, family means a lot more than a relative by blood or marriage or whatever it takes to be called a family (mind you I sometimes thinks that my closest friends as family too). The love of a family should be unconditional, and everyone should try their best to provide all they can for the people in their family, emotionally, physically, mentally, spiritually and in my KADUS blood it also mean financially.
It means the people who accept you no matter who you are, where there's no hatred or judgment. Family are the people that everyone deserves to feel secure, and comfortable with, even if they hit and bite you sometimes but that's only an indication that they pretty much exists and you can not ignore their existence.
Everything people learn comes from the way their family brought them up (presuming they have lived with them all their life), and the environment that they know best to get things for survival.
It does not matter if they are or aren't your blood relatives; if they have been there for you all their life, and will be there for you unconditionally for the rest of your life, then they are your family...