Only because I got here and my birthday happened. I'd only been eighteen a few months before I was nineteen here.
It is, at first. There are a couple like that. There's a world like mine, except that muggleborns suddenly just couldn't die. Dad's fThere's a version of Dad from that world. A Theo, from your perspective! And I've got a son here from a world where everything's exactly the same from my timeline, and things only start to change in 2001. There was a version of you from that world, too.