It's amazing how different children can be. My DS4 was reading some words at 19 months, and by 2 1/2 read very well. By 3 he could read 4th/5th grade stuff. I remember when it started he was in nursery at church at 19 months and his teacher told me he could read. I laughed of course because that couldn't be possible, then she went on to say she held something up to the class that said "God made man" but instead said to the class "God made me." DS corrected her and pointed at the last word and said "that says 'man' " I was shocked. Later that week we wrote some words down and asked them what they were and sure enough he could read. He started out by memorization it seemed, but he had so many words we weren't sure. Then before 2 he was sounding things out phonetically as well so we never could figure out how he picked it up. I never pointed to words when I read or anything, but we read tons because he always LOVED books. He was always into letters and numbers. It seemed he knew his alphabet by about 14 months and knew all the sounds letter made around that time as well.
Anyhow, I am sharing this to let you now it absolutely can happen. I also have a DD who is almost 15 mo, she has no interest in books at all...or letters or numbers. She is very bright but in a completely different way. She doesn't talk much but understands pretty much everything I say. She has only sat through a couple books in her life (when I read really quick or really overly engage her). We try every day, but it's tough. I read as she walks away sometimes.
Your DD may have initially taking interest in it because of her siblings, but if it wasn't interesting to her she wouldn't keep doing it. my DD watches DS read books...but still isn't interested....(although she loves to carry them, chew on them, and as of today...rip pages out of them). Fun times, LOL
