Asking a child why he or she has stolen something will probably not give parents the answers they need. They may need to look at what's going on in the child's life, what personal problems the child may be having, etc. Once parents find out why, corrective measures can be taken to eliminate or minimize the behavior. Don't interrogate children or force them to self-incriminate. Parents should not force their children to admit to stealing.
Children often lie to protect themselves.
If parents aren't pretty sure that their child has stolen something, they probably should not apply consequences. Instead, they should let their child know that they are skeptical, and express hope that their child will be honest with them. Parents should make sure that their children have some sort of regular income. If children have money of their own to spend as they wish, they will be more likely to buy what they want instead of stealing it. Children can earn money by doing chores around the house, etc.