Herbert Freeman Adams, in his forthcoming book "Tufts Kinsmen" states that Sarah was the daughter of Dr. Humphrey and Sarah (Pierce) Bradstreet - "Essex Instiute Historical Collection" The Essex Institute Salem, MA 1859 - pgs. 24 & 68.He also references "History of Rowley" [sorry I'm not sure of author' pg 36
As for Sarah's birth of 14 Jan 1696/7 in Rowley MA, he references "Vital Records of Rowley to 1849" Essex Institute Salem, MA 1920, pg 31 and "History of Rowley", pg 37.
Rev. John Tufts' lineage was John3, Peter2, Peter 1
The John Tufts who married Elizabeth (Pratt) Sargent had lineage John3, John2, Peter1 and they only had one child, John.
Can see where all the confusion comes from with so many John's!