In the foreward, Dan mentions that Jewish motherhood, in his definition, is a state of mind. You don't have to be Jewish, you don't have to be a mother, to treat someone like a Jewish Mother. It could be your barber, stylist, teacher, boss, co-worker, anybody can take on this role.
He tells the classic joke about the Jewish Mother who gives her son two ties for Hanukah. He, being a good son, and wanting to please his mother, wears one to their next visit. She immediately notices and asks, "What's the matter, you didn't like the other one?
It's this kind of ironic, no-win predicament that distinguishes the relationship.
The book is humorous, to be sure, and somewhat sad for those of us who grew up in this environment.