Some of the great works of SF and fantasy arose from the author saying "I wonder if SF or fantasy can be combined with <other genre>". Or with SF and fantasy combined, or subverting each other. I could name any number of examples.
As to IF: our genre (in the game model sense) began with epic fantasy (in the book setting sense). Fantasy is still the most popular form of IF, at a quick and very unscientific glance. (I'm flipping through
http://ifdb.tads.org/search .) Science fiction and horror are up there too.
I notice you missed "romance" in your list, despite it being the most popular novel genre (I think). Romance never got big in parser IF; I'm sure this is because character-centric writing is so hard to implement well in parser land. But if you include visual novels and Choice of Games type things, romance may swamp everything else.