This is fascinating! I've been told I memorised the alphabet before I was a year old... But it wasn't until I was in college that I finally memorised which hand is called 'left' and which one is 'right'. (Never had an analogous problem with compass directions.)

A possibly related deficit is that I typically think of the wrong word first when I want to name a colour; i.e. for example I want to refer to purple and I have to choke off the impulse to say 'yellow'. And yet I have letter/colour synaesthesia!

Brains are weird.