I just started looking at Robert Austin and I believe two or three Roberts have been confused. We have one born about 1638, one about 1690, and one about 1728.
Robert (born about 1638) seems to be the progenitor of this line. He had four sons, Jeremiah, Edward, Joseph, and John.
Robert (born about 1690) is the son of Jeremiah, son of Robert (born about 1638).
Robert (born 1728) is the son of Robert (born 1690).
Source material for the above is Moore, Edith Austin: A Genealogy of the Descendants of Robert Austin of Kingstown, Rhode Island. St. Petersburg, FL, June, 1951.