Teenagers commit crimes for many reasons: Outside influences, social pressures, economic standing and much more. However, parents often feel stunned when learning that a child got arrested. They cannot believe the child would make that decision.
The thing to remember is that brain development does not really end until someone is in their 20s. As mature as a teen may seem to their parents, modern research has allowed us to look closely at developmental stages of the brain, and these can help to explain thoughts and behaviors at this age. For instance, teens with lower levels of brain development tend not to think about consequences, they make more emotional decisions, they take more risks and they are generally more impulsive.
Different parts of the brain control different aspects of someone's personality. With emotional behavior, it's the limbic system. To counter this, though, the frontal lobes act as a "halting system" that tempers these reactions. When the frontal lobes are not yet fully developed, that system does not work as well as it does in adults. The emotions win out. That's why teens often make impulsive decisions, have mood swings and make choices that perplex adults.
You feel like they're just not thinking about the results, and you're right. But that may not fully be their fault. They may not have the mental ability to think about it the way they would in just five to 10 years.
If your child is facing charges, it's important to understand why the event happened and what legal options you have. Charges at this age can impact the rest of a person's life.