I never found who this Nathan Fiske belonged to. From the records I summized that he was born in the mid to late 1720's and that his first four children were born elsewhere with what I expect was his first wife, Patience (Unknown). I also guess that Patience died between 1751 and 1758 and he then married Mary (Unknown) and had the rest of his children. This would make him in his 50's when his last child was born.
Unfortunately this is nothing but speculation as I have never found anything to support my theory.
Since this Nathan is at least one generation removed from anything I have and he's not my branch I never had the time or resouces to investigate him further.
Sorry I couldn't be of any help, Bob Birt
P.S. If I had to guess at where to start I'd look at the descendants of David Fiske and Elizabeth Reed of Watertown. The data on them and their offspring is surprisingly sparse for Watertown Fisk(e)s. This Nathan could possibly be a grand child.