sowhatnow: many early memories are false. There was a great TV show about this once in the UK where they explained it and showed that other events didn't match up with the stories which had merged things from different memories.
e.g. the house they pictured themselves in was one they moved to later in their childhood based on records
The simplest test for possibly real vs imagined memory is whether you saw yourself floating downstairs or whatever. We tend not to have memories of seeing ourselves doing things simply because you never see yourself doing things!
Kids have vivid imaginations. I remember seeing all sorts of stuff but it was ususally after watching a scary episode of Dr Who (couch cushion level 3+).