Family is not about blood. It is about who is willing to hold your hand when you need it most.
Family loyalty is a phrase that refers to showing loyalty to members of your family. If there is no family loyalty among the members of a family then the family unit can not stand strong and persevere, because loyalty and love are the strength and the glue that will hold the members together against all odds and in the face of adversity. Siblings or other family members may hit or pick on each other, but no one else can do this without starting a fight.