(I don't believe in spirituality, so for me it has nothing to do with family)
To me, family is the safety net under the "Tightrope walking act" of trying to navigate life. No matter what you do, they will always love and support you, they will always be there to help you in hard times, and you can always go back there for comfort/advice/help.
My parents always told me that I could call from prison and tell them I'm in prison for murder, and they would still love me and help me in any way they could (They wouldn't be happy about what I would have done, and they would make that very clear, but they would still love me and help me out).
Also, family has nothing to do with biology, initial family is who you grew up with, be they parents or siblings. Then there is family you create, If you are close enough to someone (very good friends, spouse, etc.).
Finally, I would like to define family as the following:
Family are the people you know well enough to know that, despite all their faults, their positive features will always outshine those. And therefore, family are people you are ready to do anything for, because you know they are worth it.