"To be sure, a family is usually a biological unit.
The Jewish family is and isnt a biological unit.
We speak about ourselves as being the children of Abraham, or the children of Jacob.
But in fact, our real legacy isnt a biological one at all.
Our tribe is a very different kind of tribe.
To quote an old source, when we speak about the father of our family, the mother of our family, we say that the father of our family is God, that the mother of our family is that which is called the communal spirit of Israel.
This is not just a mystical-theological statement.
This is the way our family is constructed, it determines how the family behaves and feels."
From an essay titled "Coming Home" by Rabbi Adin Steinsaltz