Re: 1865 census for Nes, Head of household Hans Thores. (person #4031) and family on Ertserud Sæter Maalerud farm. Hans is listed as being widowed, yet Thorval and Gulbrand are listed as his sons (makes sense) while Marthea, Martin, and Ole are listed as their sons and daughter. Who is the "their"? Just a mistake on the census taker's behalf? Son Martin is my great grandfather, so I'm curious.
Without actually seeing the pages, the difference is probably that those labelled as "his sons" are from his first marriage and "deres" are from the current marriage.
Baptismal records show the mother to be Berthe Maria Gulbrandsdatter for Thorvald #142 Gulbrand #135 Anne Marthea #72 Marthin #109 Ole #111. Why the census taker use both "hans" and "deres" is difficult to explain.