I remembered back in Albuquerque, New Mexico that my son befriend a boy from his school. He was a nice boy and quiet. We let him come and visit us in our home but when we went over to his Mom and Dad's house. My son and I were shocked to see a complete mess in the house. The kitchen was bad enough to make us sick. My son tried to help him by cleaning his room and then his mom told him not to clean his room and she rampage his room up. I learned that she had a mental history and her husband just let it go with her, even if they live in the filthy house. That was years ago in the 80s.
I don't know if the girls's mother is mentally ill or that she was brought up like this too. So we don't know what their background is like in their home.