There are not much data to support the dates shown; the only 'reference' I saw quickly was in WikiTree.
Based on the surrounding profiles & the timeline, I suspect typos or number-swaps ... possibly on both the birth & death dates (e.g. could be 1738, vs 1783).
That is, John Gannaway, Sr. could have dates of 1676 to 1738 and still have a more 'reasonable' Timeline, without making parents' dates implausible. But that's all conjecture.
John Gannaway, Sr. Cannot have been the son of Marmaduke Gannaway - wrong generation. Rather, they were (it seems) brothers, who came to Virginia by 1721.
Marmaduke is said to have died “without male issue,”.
The age for Agnes Anderson is characterized as “older sister of John Gannaway l.” John Gannaway & John Gannaway ll were both witness to her husband Thomas Anderson will, and supposedly there was only one Gannaway family in Virginia.
Since her birth date is estimated at 1685, I’m moving her up a generation to daughter of Edward Gannaway & Hilda Gannaway and therefore, sister of the Maramaduke and John Gannaway who were in Virginia by 1721.
It’s still iffy; her children were born in New Kent County, Virginia, and there’s no evidence her parents came to Virginia that I’ve seen yet.