Probably from Poland (former Prussia). Immigration for the Chicago area family started around 1850. Related to Hupke, Stoerzer, Thompson(Johnson biological line), and Cooper.
Living in Chicago, Elgin, Southern Wisconsin area from the 1870s on ward.
Family rumour is that the original immigrant Kastilahn was in the Prussian army and was a border guard. Hard to identify his name but it was probably Herman. Common first names in the family are Bertha, August, Gustav, Herman, Otto, Irvin.
I have very little info on this family. Just a basic skeleton and some information on the generations after the World Wars. Anything is useful.