To me, Family goes a lot deeper than that. This would be my definition: family: Individuals sharing common threads that are commited to each other unconditionally.
This may sound vague, but, there are no conditions to being a family. You don't have to live under the same roof or share the same parents. It is not a requirement that you even be related. It is a caring of other individuals that anytime, anyplace - they know you are there for them and they are there for you.
Now THAT is family!