I once asked my dad why he taught me how to read when I was only a bit older than 3 1/2 years. His answer was: “Because you wanted me to.” I laughed and told him: “I don’t remember I was able to talk back then, how would you know? And he replied:” When I was reading, you often climbed on my lap and wanted to see what held my attention. And I understood you well enough.”
By the time I was four years old, I could read fluently (which threw my kindergarten teacher entirely off balance – but that’s a story for another time).