I’m going to give a very fringe opinion here on why some people may do horrible things, and perhaps I’m siding with Christians on this one: possession by evil spirits. Probably many on fluther are going to laugh at this, but there were quite a few cases where people were able to speak foreign languages expertly, languages they’ve been found after careful investigation to have never learnt.
The ability to speak or write a language that one has never been taught to learn is called xenoglossy. Some of these people with these abilities (pertaining to xenoglossy) are diagnosed with multiple personality disorder, or other mental disorders.
There were quite a few cases that I’ve read about relating to xenoglossy. One prominent case that comes to mind is the Billy Mulligan case. Mulligan was convicted of rape in the late seventies, and was diagnosed with multiple personality disorder. Many critics have stated that this is nonsense, but when I’d read the skeptical rebuttals I’d noticed that they had left out a few inconvenient details: one of Mulligan’s personalities was known as Abdul, and when this ego took over Billy was able to read and write in perfect Arabic. Another one of Mulligan’s personalities was named Ruben, and this ego was able to speak perfect Serbo-Croat, and do this with a heavy Slavic accent.
I’m not claiming that fraud was absolutely ruled out in many of these cases, but after reading some of them I’m convinced that fraud as an answer to some of them are highly unlikely. There are more cases of alleged xenoglossy, even more amazing than this one in my opinion, but I wanted to focus on Mulligan since it was a unique criminal case.