Hi, I am a newbie so I apologise if I am doing this wrong

I have found my G G G grandfather born in Eryrys, Denbighshire (civil parish Llanarmon-yn-Ial) his name is John Sheldon born about 1821
However I have found a man called Thomas Sheldon born about 1780 who lived in Eryrys a few doors away from John and his family. I am trying to find out if there is a link between the two, I could guess at him being his father but he could just as easily be an uncle. I believe Thomas Sheldon died aged about 94.
I don't seem to be able to find any census for the area in 1841 and wondered how else I could find out if/how these two are linked
Thanks