Briefly, there were two Jaycox men called Isaiah and both were also sometimes called Josaiah.
The OLDER of the two "Isaiah the Elder" was born before 1721 (proved by Southern Precinct tax records) and appears to have had at least two sons, James that married Deborah Purdy, and John that married ESTHER GEE. They lived in Phillipstown, where James appeared on the 1790 census.
I believe that this older ISAIAH was the son of JOSEPH, son of DAVID, son of WILLIAM, son of FRANCIS the original emigrant.My reasons for thinking this are far too involved to deal with in this forum, but I have done considerable study of this family.
The YOUNGER Isaiah/Josaiah, was born about 1751, resided in KENT, and I believe him to have beenthe son of DAVID, son of DAVID, son of WILLIAM, son of FRANCIS the original emigrant. David the father of the younger Isaiah/Josaiah appears in a biography of his several times great-grandson, and was said to have died at an early age, and lived on Water Lot 2 in Kent. This younger Isaiah had a brother DAVID, who was "of Torey inclinations" went at the time of the Revolution to Canada, and from thence to Virginia where he settled, according to this biography.
I began the study of the Jaycocks family in order to better understand the Poughkeepsie Jaycocks, those descended from FRANCIS, son of DAVID, son of WILLIAM, son of FRANCIS the original emigrant. I was fairly successful in this research.I then, out of curiosity, began to study the PUTNAM branch of the family, those that took the spelling JAYCOX for the most part, and who were descended from Joseph the brother of Francis of Poughkeepsie.
The records for the Putnam County Jaycox families are good only in a few widely scattered places, so that some lines are well understood, where others very poorly understood. There is precious little to go on in reconstructing the early generations after Joseph accurately.But, there are clues in naming patterns, tax lists, and location information.
I've done the best I possibly could, but must admit that I could well be in error. There are a lot of "probablys" and question marks in my data, and I would love to discuss early Jaycocks with anyone who has worked on these problems and might have information to offer that I did not happen to uncover in my research.