In one of the largest studies of its kind, scientists have made a fascinating discovery. Nearly 40 percent of people have a first memory that is entirely fictional.
It's not that their memories are muddled and out of sequence - but that they never happened at all.
Researchers surveyed 6,641 people about the earliest memories they had, and what age they had them, and found that 2,487 people - 38.6 percent - reported having their first memory before the age of 2. Of those people, 893 reported that their first memory was prior to 1 year of age.
And therein lies the problem.
We all know that memory is unreliable - it's why witness testimony of a crime can be such a dicey thing. But the researchers wanted to know why so many people were claiming to have long-term memories from a time before they could have formed.
Part of the survey was asking the respondents to describe the memory. The team analysed the language used by the participants, the content of the memory, the nature of the memory described - and the age of the person reporting it.
They found that the older a person was, the more likely they were to report an implausibly early first memory.
They also found that these memories were age-appropriate, which means they can't have been memories that got muddled in time. They refer to cribs, nappies, prams; or walking for the first time, or wanting to communicate before knowing how to talk.
The researchers believe that these implausible memories didn't necessarily come from nowhere, but were pieced together from photographs, knowledge of what a normal infancy entails, and stories told by other family members.
"We suggest that what a rememberer has in mind when recalling fictional improbably early memories is an episodic-memory-like mental representation consisting of remembered fragments of early experience and some facts or knowledge about their own infancy/childhood," explained psychologist Shazia Akhtar of the University of Bradford in the UK.
"Additionally, further details may be non-consciously inferred or added, e.g. that one was wearing nappy when standing in the cot. Such episodic-memory-like mental representations come, over time, to be recollectively experienced when they come to mind and so for the individual they quite simply are 'memories' which particularly point to infancy."
As for why it occurs, the researchers believe that it may have something to do with needing to complete a narrative of one's life story in one's head - although the reason for that remains unknown.
However, as the researchers point out, a positive and consistent self-narrative can correlate with a positive self-image, and an improved quality of life, so perhaps subconsciously filling in the gap in memories from our earliest years can help provide that.
But it does make you wonder how much else of your memory may have been altered by your own lying brain.
"Crucially, the person remembering [an implausible memory] doesn't know this is fictional," said psychologist Martin Conway of the University of London.
"In fact when people are told that their memories are false they often don't believe it. This is partly due to the fact that the systems that allow us to remember things are very complex, and it's not until we're five or six that we form adult-like memories due to the way that the brain develops and due to our maturing understanding of the world."
There's a comforting thought.
The paper has been published in the journal Psychological Science.