I have not proven that Henry Conn's parents are John Conn and Elizabeth Mandeville. Family history, written by Millie (Parmelia) Conn, states that Henry's mother was Elizabeth Mandeville. Millie was Henry's gdaughter through Henry's son Spencer. Spencer had a sister named Elizabeth Mandeville Conn. I am only speculating that the John Conn in Cattaragus and Chautaqua Counties of NY in the early 1800's is the father to a John Conn, Samuel Conn, and Henry Conn. Henry and Samuel both ended up in the Hancock County, IL area in the 1840's. Henry Conn died around 1850-1851. I still do not have any information that makes Henry and Samuel brothers....I'm still working on that. John Conn (who I believe may also be a brother), ended up in Erie County, PA.
I think John (the suspected father) was born in MA and his wife (who may be Elizabeth Mandeville) was born in NJ. Still looking for anyone that may know more....