Disputed origins
From https://www.wikitree.com/wiki/Garton-5
It seems unlikely that John Garton is a son of William Captain William Garton, of Christ Church Parish John Garton had a son named Richard who according to probate records of 1701 had died leaving four children. This means that Richard had to have been born no later than about 1675, and John Garton had to have been born around 1655 or earlier. But Margaret Angell, his supposed mother, was still unmarried as of her father William's will in October 1659 (she was called Margaret Angell). So these would have to be VERY crunched generations if this story is correct, with John Garton being born around 1661, Richard around 1678, and Richard's first child around 1696 at the very latest. It's possible, but it seems more likely that this relationship is just wrong.
There is no son “John” listed in William’s Will.
Additionally, we don’t know the parents of John’s wife Martha Garton
She was not a known child of John Martin & Christian Waddington
For this location and era, our best evidence is most likely found in property conveyances and wills. A good resource is Mike Marshall’s database, Colonial Settlers of Maryland and Early Virginia, as it extracts extensively from those records.
Not so good resources are FamilySearch and online trees, unless they show or cite that kind of record.