I do not believe that anyone has any documented sources, just speculation even through DNA.https://www.familytreedna.com/groups/bradford/about/results
This is a great place to learn about Richard: https://bradfordfamily.wordpress.com/
Here is what one member said "I believe the father of Richard Bradford was Richard Bradford Blessed(Babtized)December, 1611 at St. Thomas, London, England. I found a Richard Bradford son of Vespasian Bradford in the Parish Records of St. Thomas the Apostle, London, England along with the Taylor family records in the same Parish. This is why I believe that Vespasian is the father of Richard and grandfather of Richard Bradford of Charles City County, Virginia."