I suspect she did so because of the time she set for the first book, and then wanted the ages of the characters to make sense for the story line of this book. It was disconcerting to me, as the story of that year is prominent in the history of my own town. I was also disappointed that the author chose to change the date of "the year without a summer," which happened in 1816, and caused widespread famine in New York State. It seemed that the father clearly loved all of his children, and didn't treat this boy more harshly or with any less regard and love than the others.
It was hard for me to understand what made the boy in this story feel so badly about his relationship with his father. I read the first book afterward, and liked it better. I was also disappointed that the author chose to change the date of "the year with This is book 2 of a trilogy, but I read it first due to confusion about the order of the books. This is book 2 of a trilogy, but I read it first due to confusion about the order of the books.