"I was doing some reading on your paranormal website trying to find answers about an event  that happened to me," reports Jen. "Several weeks ago, my son Jeff was visiting me, then said his goodbyes and left. I heard his familiar truck starting, then he drove away.

"At that same moment, I saw what I thought was Jeff stroll through the house! Not a ghost or black mist, but a human person wearing the same clothes that Jeff had been wearing.

He walked into our kitchen, where my daughter was. I expected her and Jeff to start talking to each other, but heard nothing.

"I called out to my daughter and asked if Jeff was in the kitchen with her. She said no, that Jeff had just left the house. Shocked to hear this, I went into the kitchen and only my daughter was there. She never saw what I saw.

"It was my son I saw, and no one can tell me it wasn't.

"I started researching online and found the word "doppleganger" This seems to be what I saw. My question is: Why? What is the significance of something like this? I wonder if this is a warning of impending danger? Any light you can shed on this would be greatly appreciated."

A doppelganger usually refers to a living person who looks identical to another living person, or a single person who is in two places at once.

So what are the possibilities in your case, Jen?

• You imagined it. I believe you when you say you know it was Jeff coming back into the house, but that is the nature of some hallucinations -- they can look, sound, even feel completely real. The human brain and the mind's psychology are capable of creating these amazing illusions. It doesn't mean you're crazy or anything. It was just one of those incredible experiences. This is the strongest and most likely explanation.

There are less-likely paranormal explanations:

• Jeff was having an out-of-body experience or astral projection. While driving, he was lost in his thoughts, perhaps imagining he was back at the house to get something, and what you saw was a kind of thought-form, wraith, or living spirit. Have you asked him about this?
• A time glitch. There was a "burp" in the time continuum in which Jeff's actions at the house were somehow repeated.
• A dimensional recording. In the same way that residual hauntings are playbacks of recordings of people who have died, and their actions, perhaps the actions of living people also can be recorded and played back in some phenomenon we don't understand.
• In folkore, the sighting of such doppelgangers -- especially your own -- can be harbingers of tragedy or even death, but this is just a superstition, in my opinion. Nothing to worry about.

I actually had a similar experience many years ago. I was working in my basement office when I was sure I heard my daughter come down the stairs, pass by my desk, and go into the adjoining laundry room. I would have sworn I saw her pass from the corner of my eye as I was working.

I became curious after many minutes, however, when I didn't hear her in the laundry room and she never came back out. I went into the laundry room to see what was going on, and she wasn't there. I went upstairs to check and she said she had not gone down to the laundry room. No one had.

That was just one of the mysterious things that happened in that house.