It's been awhile since I've read this series, but watching the GoT series on HBo got me thinking about some of unresolved plots still out there.

What exactly is the deal with Daenerys targaryen's immunity to fire? I know she is the blood of the dragon and all that, but with Visery's being killed by motlen gold he obviously doesn't have the same ability to survive extreme heat.

Are all Targaryen's immune to fire, or is that just a special case with Daenerys?

I just got to wondering because I was reading an article trying to give credit to the whole R+L=Jon Snow theory, but that got me thinking about the whole blood of the dragon immunity to fire.

I don't remember which book, but I know Jon burns his hand killing one of the wights. It seems that this would be a pretty big flaw in that theory if he would supposedly not be able to be burned having dragon blood and all.
Just a thought.