In doing a quick search on the Net I see that a Sebastian Hoover was born in Germany in 1723. He had a son named Sebastian born in 1750. If my Ruth is of this family then her father would have been of the 3rd or even 4th generation. In any event, the Hoover names in Champaign county OH in 1820 sure resemble the first Sabastian's family: John, Peter, Samuel and Sabastian.
May I ask what it is that leads you to believe that Sebastian is Ruth's father, as opposed to any of the others? Do you know of any living matrilineal descendants of Mary or Ruth?