Hello. I'm of the Oklahoma Henthorne's. Just a wild guess, but I'm thinking perhaps your John was an uncle to my Mom.I'll be glad to share further info, but it may be too much to post here. If you'd care to, email me at karenray55 at yahoo.com
My Henthornes were also from Ohio/Arkansas and my grandfather had a brother John (actually 1/2 brother). My grandfather was born in 1894 I believe, so his brother would have been older than him.