Read this and answer the question. If the question is unanswerable, say "unanswerable".

Episcopalians and Presbyterians, as well as other WASPs, tend to be considerably wealthier and better educated (having graduate and post-graduate degrees per capita) than most other religious groups in United States, and are disproportionately represented in the upper reaches of American business, law and politics, especially the Republican Party. Numbers of the most wealthy and affluent American families as the Vanderbilts and the Astors, Rockefeller, Du Pont, Roosevelt, Forbes, Whitneys, the Morgans and Harrimans are Mainline Protestant families.

Affluent American families are what type of families?
Mainline Protestant