There was his first day of school and then the first time he flushed the toilet and washed his hands without having to be reminded. There was the first time he said I love you to me and the first time he offered to set the table without being asked.
When I became a stepmother to Z four years ago, he was four years old and could already walk and talk, dress himself and put himself to bed.
It's not that I thought all of his milestones were behind him, but that all of the significant ones that make parents reach for their cameras had already been lived before I met him.
But then last night something happened. I walked into the bathroom where Z was running a bath, and there he was, casually leaning against the wall, his feet in the water, his head buried in a book.
A book! Not a picture book, or a school reader, but Roald Dahl's Fantastic Mr Fox.
"Don't forget to scrub your knees," I told him.
"Yep, I'm just going to finish this chapter," he replied.
I raced out of the room and called my mum.
"He's one of us!" I squealed.