Trauma does this too. I feel like I was born the year I left home because my memories prior to that point could fit in a three minute video. And it took me two years past my move out to realize that my childhood was not, as I believed, "perfect in every way."

If you're wondering if you've got missing memories due to trauma, check where the holes are. The brain hides the parts that you can't cope with. The few memories I have from my childhood are at school because most of the abuse was at home.