The reason for your confusion is that, for well over a century, genealogists and family historians have been inventing names and marriages to fill in gaps in the records of colonial Virginia in the Tidewater region where early Pettuses lived. These inventions have been passed on as truth and even embellished by later generations of family historians. I would like for someone to show me a record of the marriage of Thomas Pettus to Elizabeth Dabney and a record proving that they had a son named Dabney. I would also like to see a record proving that someone named John Dabney Pettus married Anne Overton. Further, where is the record stating that Anne Overton was the daughter of William Overton? By record, I mean a bible record, a will, a deed, or other primary source defining the supposed relationship. There is no lack of conjectural information available in print. You should ask, did my source cite a source and was that source a reliable primary record?