I get the problems that come with including mothers; I really do. No self-respecting mother would allow her daughter to carry the ring back to Mordor, and no young woman—say Katsa in Graceling—would want her mother to come along on her missions. (When my sons were self-conscious middle-schoolers they would squirm with embarrassment if I even talked to anyone at the bus stop.)
If our stories trace journeys of self-discovery, our protagonists may need to be free of the fetters of family.