Book Theme

I am reading the book The Glass Castle by Jeannette Walls. As far as I can tell it is about a girl who's parents are homeless. She tried to help them but they tell her they don’t need help. They tell her they choose to live this way. So far I think the book its pretty alright, I really haven’t gotten that far into it yet. I think the theme right now is, to look at the world from different perspectives, because the girls mother claims that even though that she and her father are homeless, they are as happy as they've been. She wants the girl to understand that you don’t need money and things to be happy.