I mention [your family] first because it’s what matters most. Good or bad, warm or cold, strict or indulgent, it doesn’t matter, this is the most important thing, these are the relationships through which you will come to view your world, and which will shape your understanding of almost everything, directly or indirectly, both in the form of resistance and of support.”
-- The Author  (Section 1 – Letter to an Unborn Daughter)

Importance: As the author explains his purposes for writing the essays in this collection (that is: to introduce some of the many aspects of being alive to his unborn child), he indicates that of all the objects he could discuss, family is the most important. That said, it is interesting to note how, in the rest of the collection, references to family are, for the most part, minimal.

…anyone who has experienced [porpoises], rising not only out of the deep, but out of time itself, unchanged as...
-- The Author  (Section 2 – Porpoises.)