A colleague of mine, whose Mother was a Medium, says that he has experienced spirit visitations and visions. He is an intelligent, educated guy and genuinely believes in some form of "spirit manifestation"
Some people have minds that are much more receptive to bullshit than others. I don't believe it has any correlation with intelligence, more to do with some people being firmer set in their view of the world than others. Quite simply some want to believe and as a result, see things others don't. It's kind of obvious that someone whose mum was a 'medium' would go on to experience various 'strange goings on' but I strongly doubt he would have experienced the same things were his mum a bit more normal.