generally when you are younger, it is possible to have stong connection to things that alot of adults can not see. it is possible to have seen a ghost when you where 3-4, because you would have had this sense back then, they only disappear when you stop believing or are not scared anymore,
remember ghosts and apparitions can not hurt you, plus dont bother with phycics, because they are most proberly shams.
I have seen many ghosts upto the age of about 16, the last was an old lady, which signaling need for attention, safety and comfort. learn not to be scared, because we will be ghosts, one day.
and the scitz thing, my 3 bros all have seen the samething and are not scitz so there