1920 Census - Mulvaneys at 270 Van Brunt St.

This is the 1920 census, showing the Mulvaney family at 270 Van Brunt St. Julia gives her age as 50 (yielding an approximate birth year of 1870), and says she's widowed. Only Veronica and Harold have attended school in the past year. James is a fireman for the city, Grace a salesgirl at a stationery store, Mary (this is Auntie Mae, right?) does clerical work at a drug store, William has no job, and Thomas is a helper at a shipyard. (This is interesting to me because Betty and John have said that Harold died because he was hit in the head on the pier while working at Todd Shipyards - it seems he eventually followed his older brother into a shipyard job.) Another thing I noticed is that William, at 18, has "no" listed for both whether able to read and whether able to write. Why would that be? Nana has no answer listed for either, but at 10, perhaps her reading and writing abilities were not quite so fluent as to warrant a "yes," but not quite so bad as to warrant a "no"? If you scroll through the page, most of the people who have no response in the reading and writing columns are school-aged children.