Well this is more to do with the way the brain grows and develops. We are wired to pick up language during our early stages of development. That's not to say that it is impossible for an adult, only that as age increases our ability to learn languages decreases. Sure, some of it might be hang ups, but a lot of it is the wiring of the brain.

Of course that does not give adults the excuse to make no effort at all! I'm learning Japanese at the moment, and I tell you if you think German is hard.... oh boy...

One thing that I think makes a difference is an awareness of pronunciation. I never had exposure to a second language as a child, but I did grow up in 3 different English speaking countries and was constantly teased about my accent - but I learned to adapt it quickly. I think this gave me a big advantage when learning German, and has helped me a lot with understanding some of the rhythms of Japanese.

I must admit that I am surprised that so many expats think that Zug is pronounced "Zooog" - I've even been subtly corrected on many occassions when I pronounce it correctly. How can someone live somewhere and hear a word so many times, but have a totally different memory of it in their head (unless their entire experience of hearing the word comes from only other English speakers mispronouncing it?)