I was following the line from Moses Johnson to Simeon Johnson to Elizabeth Johnson, all descendants of Capt. John Johnson of Roxbury, Massachusetts. It looks like there is disagreement as to which Elizabeth Johnson married John Rollins, but because of the names (they named their first son Simeon and she is named Elizabeth), I believe that the sources that state that she is the daughter of Simeon and Elizabeth (Gardner) Johnson are correct.
Now we come to John Porter Johnson who a number of sources say is the son of John Rollins and Elizabeth Johnson. Other sources say that John Porter came to America from England with brothers James and Henry. The problem is that John Porter's history is tied up with early Mormon settlers and I cannot find a definitive source. I suspect that John Porter Rollins is NOT the son of John Rollins and Elizabeth Johnson.
The biography of John Porter Rollins' son, James Henry Rollins, says both that his father was born in Vermont and that his father came to America with two brothers. Henry Rollins is an early British Mormon convert but there's no indication that he is related to John Porter.
If anyone has good sources that are not various Ancestry trees, I would appreciate a hand here in sorting the pedigree of John Porter Rollins out.