Hey dude, check out this:
If i were to start my robotics journey again, here is where I would start
Look at all the lovely, ready to use tutorials:
That's pretty neat.
I don't think anything really determines what a microcontroller is programmed in. The microcontroller is just a piece of hardware with electronics in it. A manufacturer just creates the chip and chooses a programming language to program their chip in and specifies in it. The PICs are capable of being programmed in a few languages, but it's very very costly.
I'm not too sure about this, but it's mostely just a manufacturer's decision. Though, there may be something within the chip that only allows it to understand one language. I don't know. I wouldn't go trying to messing with hacking them, although it's probably possible.
It would be worth looking into though.
If you find anything out, I am interested in seeing it.