What's the difference between 因为什么 and 为什么? Usually when first learning Chinese we learn that 为什么 means "why".  However, I recently encountered 因为什么, and I'm wondering if it's different.


  你因为什么给关进去?
  Why were you put in?
  (玛帝尔达 (Matilda), page 114; English version pdf page 101)


It directly combines 因为 = "because" with 什么 = "what", so it looks like it means "for what reason" or "why", i.e., it's the same as 为什么.  I'm not sure if there's any distinction though.

Question: What's the difference between 因为什么 and 为什么?
I would say you could opt to translate them these two different ways:


为什么 = why?
因为什么 = how come?


Which matches to English fairly well.

因为什么, though, is usually part of a larger sentence structure like [...]是因为什么原因[...].