Jack's sister was incredulous that he had gotten away with his misbehavior.
Childhood lying has many causes, including the need to maintain parental approval, to gain attention, to avoid disappointing others, to evade the consequences of misbehavior, or to avoid responsibility.
This does not mean you should sit back and accept the misbehavior, though.
If you attend a Catholic school, or are worried your child is traveling down the wrong path while enrolled in this form of education, you may want to meet with the school and your child separately to get to the bottom of her misbehavior.
If the misbehavior continues, take away a privilege as your consequence.