The first systems for computerized text processing suffered from the fact that their target printing facilities were very different and hence they must have been "programmed".
The standard GenCode (author William W. Tunnicliffe) was therefore developed, which allowed to mark the general (generic) print output in the text, and a special compiler customized the output for a particular output device.
The "real father" of markup languages is often considered Charles Goldfarb from IBM, which developed early seventies the language IBM GML.