Depression is not your fault or caused by something you did wrong. Many things can contribute to depression. The following includes teenage depression symptoms:

• Factors such as hormones or brain chemistry.
• Trauma like physical and sexual abuse or violence; rejection or neglect by loved ones; neglect; major changes in life; and ongoing high levels of stress.
• Genetics. Sometimes depression runs in families. Teens whose parents who have experienced depression are more likely to experience it themselves. (View Source)