Fathergone was born in Boston on the 25th of 10th month (December — Thanks, Lori!), 1638.* He was, obviously, a posthumous child. His baptismal record calls him "Fathergone son of William Dyneley our gone brother" (see Boston Births, Baptisms, Marriages, and Deaths 1630-1699, published by the Boston Record Commissioners in 1883, pg. 7).
*Note: I am not quite sure how to interpret the First Church's use of month names. Since they were still using the Julian calendar, the first day of the year would have been Lady Day (March 25th), but I'm not sure which month is "1st month." March? April? If anyone is more knowledgeable about this issue, please help me out. For now, I'll just quote the original dating system so I don't misinterpret it.