Here's a study from 2012 that shows IE users are prone to be significantly older than Chrome users, suggesting that your website appeals mainly to an older audience. (http://www.liveintent.com/news/advertising-technology/browse...)
The book seems really cute, as well, and a clever idea. If I was older and had a kid, I might have even considered buying it.
Perhaps something about it appeals to grandparents.
Without looking up demographics, I would bet that such people have a higher-than average likelihood of being a parent (or grandparent) with some disposable income.