Do you believe...

I've been thinking about the existence of the supernatural these few days. Ok, it's partially cos of my weird dreams, but not that I am superstitious or what so ever. You can say I'm curious. And I've been asking alot of people (yea, including my juniors, how rare) for their opinions. But still, I dunno. I think I'm more interested in their own experience?
Up til now, I am still not sure if I believe in those stuffs. I mean, my friends and reletives whom i believe will not lie to me said that they've come into contact with 'them'. And few times I thought I saw something at the corner of my eye, but i think that's just my imagination.
Last year, I came up with a theory as why people are able to see 'things'. People who can see these things might have some kind of thingum in their brain which allows them to see some kind of immaginary images. In other words, they are mentally unstable.
But after hearing what happened to my uncle, I'm having doubts. Apparently, the WHOLE FAMILY heard their closets being hit simultaneously. And the master's bedroom locked by itself.
Now, how is it possible for a family of 4 to be able to experience the same "imaginary" thing at the same time? I shall scratch my head.
Maybe there's really things that science cannot explain?