What is the significance of the brightly colored house in Chapter Two?

The sign on the front of the brightly, colored house indicates that the house has been sold, which causes the twins to feel a bit saddened, and they complete their walk home in silence. Along the way, Alex thinks of their father who had passed away a year ago and about how they spent their 11th birthday without him. She also remembers that their mother sold her father's bookstore along with the house they had just walked past as they could no longer afford to live there.