Fetal brains are pretty useless in the memory and recall area. A new born is pretty much not a real human being due to the fact its brain is not fully developed. 'Fully developed'
brains don't happen until age 3. And then that is a misnomer because the brain is always developing, learning, changing throughout a lifetime.
The connections needed to file and store memory files and the software required to retrieve that data doesn't get set into a human brain until at the least 6 months after birth.
Around the time a baby starts saying its first word is when long term memory retrieval starts setting in strong enough to make it possible to recall that data later in life. However recall of memories is under construction and isn't fully online until age three, with it growing stronger and better at this skill from month 6 to age 3.
Typically 2 years old is the time that real, fully formed long term memories are stored 'permanently' on the storage areas of the brain and are fully accessible/retrievable (recall).
http://www.nbcnews.com/health/first-memo...-1C6436064 may be helpful.
If you are possessed of an
eidetic memory in any form it may be possible to retrieve data from as far back as 6 months, or whenever your brain made those connections necessary for your brain to store data and retrieve it.
Not all parts of memory and recall develop at the same time. There is physical memory (which allows us to do repetitive tasks, walk, run, ride a bike) which starts setting in around the time baby can roll over, but isn't formed fully enough until baby starts walking.
Then there are emotions memories, which allow us to recall how we felt. "Logical" memories which allow us to store and retrieve learned data (math, reading, writing, history). And there is also personal experience memories.
Understand most people rarely forget stuff. Memories are 'stored' in the brain and remain in the brain until the brain is damaged or injured. The problem with 'forgetting' is not a loss of memories, but an inability to
retrieve that data. People with Eidetic Memories usually have a finer tuned, sharper recall ability. They store data and have a better retrieval system.
Amnesia victims still have their memories, they just are unable to access, retrive and open files. Its sort of like having a hard drive with a corrupt mother board - all the data is still on the hard drive, just that the paging/retrieval software or hardware is corrupt, missing or damaged.
I think what may really be happening is that your folks or family have talked about this holiday around you and you are recalling their recall of memories of this holiday which your brain stored in a way to make it a personal memory.