My mum seems to know all of ours. Without looking it up (and they're not all recorded) I couldn't tell you much about my DC. I don't know what they weighed at birth, what day of the week it was or how long the labours were. I also don't know when they first sat, stood, walked or spoke or what their first words were.
Just me? They're 21 and 19yo now, but I don't think I've ever really remembered this stuff