Look up
hyperlexia. The TL;DR is that early reading is recognized by some as a
disability these days, which is mind-blowing to say the least. Per Wikipedia, 80%+ of early readers are autistic.
We initially thought my youngest was a super genius for teaching himself to read from age 3. Following in my footsteps - I taught myself how to read early at a similar age.
But it seems to be the case that for NTs, no matter how smart they are, they will typically not learn to read until about age 5. We tried a lot with my oldest son, and I will admit at frustration that he was clearly intelligent but refused to "grok" reading, while I clearly remembered being an early reader.
We were much less insistent on early reading with my youngest son. He never had the attention span to sit through a book, unlike my NT son at the same age. So naturally when the youngest son started reading on his own at a ridiculously early age - through zero effort on our part - we mistook that for genius. He's gifted, but not
that gifted.