I don't know where I got the information.Maybe from LDS (which is sometimes unreliable) or from the internet somewhere (ditto). About a year ago I lost my hard drive which had much of that source information on it.
I have John Duty b. July 4, 1691 - no info as to where or wife's name, but sons Matthew, William and Richard.Richard is supposed to be the father of Samuel Duty (b. 1788) who married Fannie Kelly Harris and had 13 daughters, and Sarah Duty b. 1793 who married Willis Harris.So Samuel and Sarah Duty who were siblings married Fannie Kelly and Willis who were also siblings.