@leolab
Something different is something scary
Not directly related to argument at hand, but... At some point I started to think this statement is a lie that people want to hear. The more I cross-reference facts the more I confirm it to myself.
This primarly based on the fact that humanity is pretty reasonable. Even most ridiculous and wierd behaviours has reason or cause to it, every person guided by logic provided you can distinguish it within him. Xenophobia is a simple explaination of much more complex factors that convenient to hear, but actually just fitting answer to problem at hand.
Second reasoning is innate sense of curiosity within humans. While humans in general have wide range of amount of all qualities, we can pretty much state as fact that humanity loves to expand and to consume foreign entities for own benefit.
Then comes logic: what circumstances could bring fear from difference? Setting direct threat aside, it's when difference change established working mechanism making it unusable. I.e. malfunction of fault from the inside. And if it's a flaw that obstructs proper work of social mechanisms you can't really say its "fear because something is different". By that logic condemned criminals are just "feared because they are different".