If you think his parents were John and Susan Lock found 1850/1860 Texas County, MO, then pursue that angle. They were Indiana natives and that agrees with their son's 1880 enumeration in the Arkansas School for the Blind. Perhaps research of the parent(s)' probate record(s) will provide needed confirmation? Don't think you'll find Texas records confirming his parents? FYI, his brother Jonas H. also relocated to Arkansas.