Is it normal for a 12yo to have insomnia?

No. A healthy 12 yo should drift off to sleep when tired & awake rested. When this does not occur, an evaluation for physical or emotional factors that interfere is needed. Medical conditions such as hyperthroidism may be present. Emotional stress from school, developmental changes, social attachment, etc.May be involved. Have a talk with your child & destress situations if you can & schedule a dr visit.
No. Insomnia is not normal in a 12 year old. See your pediatrician to have an evaluation since there are many causes both physical and psychological that can cause this.