Time to pitch my two cents in (I can hear all of you groaning, but bare with me)
Children are impressionable, they don't yet know that the idea of seeing ghosts and things is frowned upon by society, and they have no problems with telling their parents what they've seen, while an older person may fear being considered weird or crazy. I've heard the theory that spirits are drawn to children, also. But honestly? What I believe?
It's under the same principle as the greek/roman mythology. They didn't understand natural phenomenon, and so they thought of dieties to explain it. Little children don't yet understand things like shadows and lightening and houses creaking as they settle at night, and so they come up with paranormal explanations, and their parents want to believe that they are pure or in tune with the spirit world, while it's only their young minds grasping new situations they don't yet understand, ehich would explain why the "gift" goes away when we get older. It also helps that young children have huge imaginations and may actually believe they're seeing things when it's all in their own mind.
On the other hand, I'm not denying that maybe they do have a link, and maybe they do see things others don't. Sometimes strange and unexplainable things do happen...!
Edited by Agent D. Scully, 15 May 2011 - 11:14 PM.