My son, who is ten "started to read" when he was about 4-5...meaning he could recognize letters, signs, very simple words. He was in a Piaget-based university lab preschool program that provided a "print-rich atmosphere" but no reading instruction. Then he went to a Montessori K class, and a couple months of first grade there. I pulled him out just before he was 7, to homeschool (we're unschoolers.) At that time, he HATED to read, was not even reading simple easy readers. Hated hated hated reading. So i didnt press it.
In the past year, when he was 9, he started reading novels, like Bridge to Teribithia, Charlie Bone, and The Chronicles of Narnia. How did he learn to read so well?
Videogames. Seriously, i have met so so many unschoolers who say their kids' reading skills really took off with exposure to videogames and computer games. When he left school, my son needed help reading all the text on his games (Animal Crossing is a good one for having TONS of stuff to read), gradually he would ask me less often, until i eventually noticed he didnt ask me at all. And of course, we were reading together every night as well (Harry Potter, Eragon, Wrinkle in Time, Bartimaeus, So You Want To Be A Wizard, etc). So he learned to read (and actually really likes it now.)
But he didnt like to write. He still doesnt like to write by hand (i think it feels to slow for him), but after discovering a love of online RPGs (role playing games...Everquest, World of Warcraft, City of Heroes, Runescape, Etc) which involve so much typing to communicate w/ fellow players, he really got good at it. His immersion in fantasy (knights and warriors and magic) led to him writing his own stories on the computer, about the heroes/characters he created in his games. In my homeschool group, mothers have been known to say things like "Boys just don't like to write!" or complain about how their boys resist the required journal writing about their day. My boy can choose to write about what he loves, and does so willingly because the subject matter is important to him. He's so passionate about his interests and i love that!
So this is my longwinded way of saying that i think a more "natural" age for kids to learn to read well is around 9 instead of 5 (not saying if a kid wants to learn earlier that isnt ok too), and that its completely normal. I also think that the best way to encourage a love of reading is to spend time together reading to your child, live in a "print rich environment" with plenty of opportunities for reading (for us this includes computer, videogames, and closed captioning on tv, as well as posters ,maps, books, etc...oh and comics are great too!), and giving them materials to read about subjects they love.
Katherine