My younger sister is 15 years old. We grow up in a single parent family. She has the bad habit of stealing money, which began when she was very young and still continues.
We punished her - sometimes we will hit her - and we told her very grimly that she can not do this again, but to no effect. After a few days, she forgot. She loves lying to us after she stole money. I know that the physical and verbal punishment is not effective, so I'm going to tell her the worse consequence is taking her to the police the next time she does it.
We have tried asking her why, but she did not tell us. She was always silent. We give her a limited amount of money to spend every day, but she wants to buy many things she likes.
How can her behavior be stopped?