What can be the reason for certain people that are very difficult to have a straightforward conversation with?

I have known some people like this that have always been like this as fa as I know. They never usually answer your questions directly and it is "talking in circles" with them, really frustrating. Sometimes it makes you wonder if they are even aware what you are asking them. Seems like they avoid a direct one on one conversation and you wonder if they do this just with you or everyone.