My earliest memory is either slightly after the age of two, or possibly slightly before, depending on which one came first, and if it was the latter, when it happened.
Memory with a date on it: We were in a big building with high dim halls. They took me to a window into a room. There was someone there, touching a baby in a glass box. That was interesting. They pointed at another baby, in a crib right below the window. She was wearing a blue blanket. It was my little sister.
My little sister was born not quite three months after my second birthday.
Memory without a date: I was downstairs in the Big House looking up the hole they'd made in the second floor for the stairs. I was MAD. I wanted to be up there too, but Mama had said I could not be, because I was too heavy and I would fall through. I knew they were pulling one over on me, though. THEY were bigger than I was, and THEY were not falling through. It was untrue, and therefore, they were lying to me.
Many years later, I brought this up to Mama. She explained: they had just put the plywood down, but it wasn't nailed yet. They were walking very carefully, making sure to stay over the beams. If they'd gone running off like I surely would have, they'd have fallen through. But they couldn't trust me to not go running off, so downstairs I stayed. MAD. (Mama was impressed that I'd remembered that. It had made an impression, though.)