Recently, i had to understand the design of a small program written in a language i had no idea about (ABAP, if you must know). I could figure it out without too much difficulty.

I realize that mastering a new language is a completely different ball game, but purely understanding the intent of code (specifically production standard code, which is not necessarily complex) in any language is straight forward, if you already know a couple of languages (preferably one procedural/OO and one functional).

Is this generally true? Are all programming languages made up of similar constructs like loops, conditional statements and message passing between functions? Are there non-esoteric languages that a typical Java/Ruby/Haskell programmer would not be able to make sense of? Do all languages have a common origin?