Captain John Johnson
According to an excellent source - http://www.mayflowerfamilies.com/cooke/d21.htm, John Johnson had 5 undisputed children: Mary, Issac, Humphrey, Elizabeth, and Sarah.
John was married to (1) Mary Heath (2) Margery (?Scudder) and (3) Grace Fawer nee Negus. His 5 children listed above are the children of Mary Heath and himself.
It is commonly claimed also that he had a son, John Johnson. Other children mentioned for him: Joseph Johnson, Hannah Johnson.
The MP above seems to be conflating two John Johnsons. So, for intance, Humphrey Johnson, my ancestor is listed both as brother and son! To make things more confusing, John Johnson, father of Humphrey et al, was the son of a John Johnson who stayed behind in England (wife Hannah Throckmorton).
I have started a Captain John Johnson of Roxbury, MA project. If you can help clarify the early generations, let me know.
Private User is the curator of this MP and I have already written to her.