I don't know who Kelly is, but I would be looking for another source than the one you've quoted above.
There is something very odd about the dates that supposedly come from the family Bible. I couldn't open the Google reference, so I used this one
And if Dorothea, was born in 1728, married in 1762 and then had 3 sons on 1763, 1775 and 1778 (when she was 50).
I'd be asking myself, why did she marry so late? Why the gap from 1763-1775? And how believable is the birth of 1778 when she was 50? (Perhaps not impossible, but fairly unusual).
I'm becoming cynical in my old age, but when an article seems to indicate that it is quoting sources (land records, family bibles) but actually doesn't give a reference for that information, and some of the dates just don't add up, then I start to think - Hmm - how much of that can I actually believe?