Yusuke Shinyama speculates: what would Lisp look like if it had been invented by speakers of a consistently postfix language like Japanese? Might it be written postfix instead of prefix?
Maybe so. But this is superficial. The
car of a Lisp form is special because it's the head, not because it's first; as long as there are
rest operators, it makes no difference whether the head is stored first or last or even in the middle. So while a postfix Lisp looks different, this is only a superficial matter of syntax; Lisp would work the same way if it had been invented in Japan.
Forth, though, might be dramatically affected — not in nature but in timing. Despite its simplicity, Forth appeared rather late: it was developed in the 1960s and not publicized until 1970, which was too late to become part of the cultural foundation of computing. I suspect this was an anomaly; Forth is so simple that it could easily have been discovered earlier, had anyone bothered to explore postfix notation. Speakers of a postfix natural language have an obvious example to encourage them. (Postfix mathematical notation would be an even stronger encouragement. IIUC Japanese arithmetic words are infix, so a Japanese-inspired notation would also be infix; postfix arithmetic could arise more naturally in a natlang where arithmetic operators are postpositions, and postpositional phrases follow their head noun, but this is not a common combination.)
If Forth had been known by the mid-1950s, it could have outcompeted Fortran to become the canonical high-level language. This would have exerted significant pressure on hardware: machines would be designed to run Forth, much as they're designed to run C today, so there would be a lot of stack machines. Since Forth makes such a good assembly language for such machines, there would be less pressure to develop other high-level languages. Programmers accustomed to its simplicity and flexibility and convenience would see all proposed alternatives as unusable and crippled and insanely complex, so other language families could go unexplored. Forth and its descendants might rule computing unchallenged for decades, until some long-delayed development made tree languages competitive.
History could be different. Lisp, Fortran, Algol — all the great old language families — might not exist, if the pioneers of computing had spoken a head-last natural language and found Forth first.