What general aspects of society did James McBride indirectly criticize or challenge in The Color of Water?

In The Color of Water, James McBride examines racism, indoctrination, and abuse in society, as well as the politics of identity. A memoir and homage to his mother, The Color of Water addresses both McBride's and his mother's personal history. Born in Poland and of Jewish descent, McBride's mother emigrated to the United States under the name Ruth (originally Rachel Shilsky). She faced ethnic prejudice at school while also paying witness to the racist attitudes of her family, namely her father. This theme is carried through to the next generation when her biracial children are subjected to racism throughout their upbringing in the 1960s. Here, the societies of both Europe and the United States find themselves in the same boat. Presumably, the title itself calls upon an old idiom: that blood is thicker than water, suggesting that family ties are deeper than all others. It is not so in this case.
Doctrine and practice are also critiqued here. Ruth's father, a rabbi, is emotionally manipulative and sexually abusive to his daughters. His threats of sending his wife and children back to Poland to face sure persecution at the hands of Russians and Germans is juxtaposed against his own racist attitudes toward the African Americans in their community, with whom he interfaces through the family store. Ruth ultimately breaks free from this narrative in order to pursue her own life following a problematic pregnancy with her African American boyfriend, which prompts her move to New York for an abortion. She ultimately opens the New Brown Memorial Church along with McBride's father, practicing her own doctrine.
One final critique points directly toward the politics of identity as experienced by both Ruth and James. One point that lends credence to this argument is Ruth's answer to James's question about her race, which she answers simply by saying that she is "light-skinned," rather than agreeing that she is white. Identity here is treated as a choice to be put into practice rather than as an immutable category decided by skin color. Ruth's hard work and sacrifice for the education of her children and her demands on them that they also work hard and reap the benefits of the education she provides following the death of her second husband weave into this critique the suggestion that identity, while chosen, is also earned. Ruth's choice to live a life in keeping with her personal beliefs came with great sacrifice and tumult, but these sacrifices and the love and beliefs instilled in her children give way to McBride's ultimate production of The Color of Water.