Bumps in the Night

If we are assuming you are not a basketcase, and we're throwing out paranormal or the supernatural (which I think is a good idea). Then we're left with one class of explanation: You were being fooled.Now for the hard part. How were you being fooled?
We cannot rule out sensory mistakes... our minds and senses play tricks on us all the time. Even groups and multiple families are not immune to such mistakes. But... this path leads us to the answer of "in reality, it was nothing at all, it was all imagination."
Although quite possibly true, it's a rather boring explanation, so I will move onto the funner stuff:Assuming the sounds/visuals were actually real, how were you fooled into thinking of ghosts?This type of question is one of the hardest to answer. Because, by definition, if you knew what you were looking for you'd already have your answer.
So how do you uncover something when you have no idea what you're looking for?Track whatever information you can.
Do not rely on your memory.
Look for patterns or anything recognizable.First, forget about any experience in the past. Such experiences are already tainted by non-objective memory, rationalizing and group-interaction.
Then, record everything you can whenever you have an unknown experience.
What was the sound?
What was the visual?
What was it closest to sounding like/looking like?
What happened? - Be specific and as detailed as possible
What time was it?
What day was it?
What was the ambiant temperature?Then you can start answering other questions later:
-Does it have any pattern in when it occurs?
-Is there any pattern to how it occurs?Also, cameras are your friend. Set up cheap, easy cameras in multiple areas to try and pick up sounds/visuals while you are away. Carry one with you to record anything when you're present.I, for one, would love such a supernatural-seeming puzzle to occur in my home. But then again, I'm a bit obsessive-compulsive in figuring such things out. Especially where recording accuracy is concerned. Most other people just don't care that much. Oh... so even if we do get "good guesses", we'll likely never know for sure.
You are almost invariably cornered into the answer of "I heard/saw some stuff, not sure what it was, I think it could have been this..."A few questions just for kicks, then:
Did things always happen at night? Or just mostly? How often? Every night? Once or twice a month? The higher the freguency of occurance, the easier it is to track and discover. More in the winter? Summer? No where in the rules of reality does it state that your unknown issues are all from a single cause. It certainly could be a combination of one or two or more things. Add in the fact that as soon as one starts listening for "unexplained noises/visuals"... one is assured to find them. The chances that none were imagined stretches any sense of credibility.

I wasn't trying to lean so close to hallucinatory in the sense of "totally made up." That seems a bit too dismissive and easy for me. By "being fooled" I meant more towards the sense that you heard some things, and were mistaken in thinking they were from certain specific sources. No specifics are required, I meant the term ghosts to encompass a vast array of unspecified sources. As a side note, I personally don't know of any difference between "demons/evil spirits" and "ghosts." The supernatural, paranormal, and religious spirits are all perfect synonyms to me. Different names from different cultural/social backgrounds for the same fundamentally unknown types of entities. I don't think any of them exist, but I certainly don't know everything This is the kind of sentence that lets us easily slip into a feeling that it must be unexplainable. Which then only leads us into thinking of the sources that we are assuming are not even real. We must be clear that by "there would be nothing" we actually mean "our limited investigation lead to nothing." It is important to admit that your investigation was not all-encompassing. Perhaps you only looked for people-sized objects in the room. Perhaps you only looked under the chairs and sofas. I doubt you ripped the walls or floors open. I also doubt you did an extensive search using expensive equipment to search for minute traces of small creatures. Not that I blame you at all, such things are easily deemed "over the line" or "unrequired." But, well, we have to be clear that your investigation was obviously limited in some way, otherwise we would have found the cause. That is, if we are assuming the cause is mundane. Recognizing patterns is very helpful in determining a mundane cause. It may help to identify the actual cause, but at a minimum it should help to eliminate other possibilities. The problem with attempting to identify patterns from memory is that our brains like patterns. We like patterns so much that our brains will edit our memories to create patterns where none actually exist. Without recorded information, we are at a loss to know if our memories are correct representations of what actually did happen. Good to hear you're getting some nice ideas from the discussion.

No, that's not a better way to put it, that's a confusion and dishonest way of putting it.The fact that you failed to uncover a mundane explanation for your story does not point to the conclusion that there isn't one. It only shows that your search for a mundane explanation was too limited in order to find one.Everything we KNOW to exist in reality shares one thing in common. At least someone, somewhere, at some time, has verifiably identified a difference between the real, existing thing and imagination.
Since your story does not include such a thing, we are unable to say that you KNOW ghosts exist.You can present all the nice claims you like, without being able to verifiably differentiate between your story being real or imagined... it will forever stay in the realm of imagination.