I've gotten one generation beyond Israel, but I know very little about them.Israel's parents were Isaac Yost (Israel seems to have been the first generation that used the "Yoast" spelling) and Mary A. ___.Isaac was born in 1830 and Mary in 1832.They were both born in PA (according to the census) and were living in Philadelphia in 1860.
I suspect that they were Pennsylvania Dutch -- probably from Lancaster or York County -- but so far, I haven't been able to prove that.
I don't know of a Josiah Yoast -- but he could well have been part of the same family.
If any of this sounds like a connection, give me a yell!