I've read a few counter comments here which indicate I may be off in my thinking. That said I don't think your one example proves my theory wrong simply becaus

I've read a few counter comments here which indicate I may be off in my thinking. That said I don't think your one example proves my theory wrong simply because I didn't say that someone couldn't have other interests what I believe I was trying to say is that they aren't "all over the place". The question really is "how many pet topics" do they have I guess. I would just think that that type of brain has to be more focused. I've also noticed this with Physicians as well (anecdote of course). I've told them different things and they tend to react as if "wow who would know that or think of that" type of stuff. Because my brain (and I'm not even saying this is an advantage) tends to be all over the place in what I find interesting. So maybe it's a matter of degree not an absolute that can be measured.