Kinghorn Family Genealogy Forum
I am also a descendant of this family. The John Kinghorn you mention is my 4th Great Grandfather. My line departs from yours in that I am descended from George Kinghorn, the youngest brother of Isobel (or Isabella). I do have quite a bit of information about George, his family and (at least some of) his descendants if you are interested.
Briefly, you may know that George and his family joined the Mormon church in Scotland and immigrated to America, staying for a time in the St. Louis area (on the Illinois side) where George died. It appears that many of the rest of the family went to Utah where some eventually settled in Idaho. Others ended up in Nebraska and Washington state.
I would be very interested in learning about your line and what you know about the Kinghorn line in Scotland.