Early but not totally implausible. My mother taught me to read when I was four and I could write before I was five. It was a pain at school where I had to endure a couple of years of reading simple John and Jane books while everyone else was catching up. Unfortunately, while I could write, I never developed the technical skill of writing legibly and fast so even I have difficulty in deciphering quite a lot of my writing. More than thirty five years of using computers to create documents hasn't improved things either.

When one of our kids was around 3, we would write down the stories that he would dictate, which he would then illustrate. It was a lot of fun and I'm glad we still have those.

I was reading to my kindergarten class when I was 4, self-taught (lots of Sesame Street and Electric Company), and I am not remotely brilliant.

I can certainly believe someone writing at 3, although it's pretty damned impressive.

Haha, of course it wasn't any good! But yes I was reading (terribly) and "writing" (awfully) at age 3.

I trade a remarkably early start in literacy for literally 0 math skills.