Markup Language Family Tree

                         RUNOFF                      "Generic Coding"                 "Editorial Structure Tags"
                   (Jerome Saltzer, 1964)         (William Tunnicliffe, 1967)          (Stanley Rice, pre-1970)
                            |                               |                                     |
                            |                               |                                     |
        TeX          roff - nroff - troff                   |-------------------------------------|
 (Don Knuth, 1977)   (Josef Osanna, 1973)                   |
                                                           GML
                                                    (Charles Goldfarb, 1969)
                                                            |                       SCRIBE
                                                            |                   (Brian Reid, 1980)
                                                            |                          |
                                                            |--------------------------|
                                                          SGML
                                                      (Standard, 1980)
                                                     |                |
                                                     |                |
                                                   HTML              XML
                                            (Berners-Lee, 1990)    (Standard, 1998)

Updated to show the contributions of Stanley Rice and William Tunnicliffe, see:

http://en.wikipedia.org/wiki/Markup_language and
http://www.digitalhumanities.org/companion/view?docId=blackwell/9781405103213/9781405103213.xml&chunk.id=ss1-3-5