Why is Ama disappointed in her daughter in the novel, The Wangs Vs The World?

Ama believes her daughter, Kathy, to be far too Americanized, which she sees as a disappointment. The story makes clear, however, that Ama's judgement of Kathy is unfair: Kathy is a military wife who has kept her family together and is now raising her grandchildren while their own mother (Kathy's daughter) is in the military.