My earliest memories that I feel confident about saying "yes, that definitely happened" are from our time living in Cyprus. I guess I was around five or six. I remember having a yellow sun dress with tassles. I remember great, noisy, stinky pelicans everywhere, stealing food from your plate. I remember finding lizards in wardrobes, I remember huge, crushing waves sweeping us out of dinghies at Curium beach, and I remember sand so hot you couldn't walk barefoot on it. I have very vivid memories of us finding a snake in the back garden one day, and Mum keeping us kids inside the house until an old man came and killed it. As a snake-keeping adult, that memory rests very uneasily with me now.
Still, I have no idea what kind of snake that was back in Cyprus all those years ago, so I suppose it could have been deadly (unlikely, but this was a long time ago so there's no point worrying about it now).
Anyway, those are my earliest definite memories, and we have extensive photo albums to prove it all really happened. Take that, evil, memory-faking brain.