Certainly I am related to but not descended from my sister as I am related to but not descended from my mother's sister.

If we limit the meaning of the phrase descended from to refer only to direct male lineage, then, of course, to say we are all descended from Charlemagne or Muhamed is ludicrous, but if we allow all branches of both matrilineal and partilineal descent then (except for the cases of, e.g., pure-blood Australian aborigines, if there are any) it seems to me almost self-evident.