Yes, everyone that lives in your household that is of legal driving age needs to be listed on the policy. The reason is they have access to the car. Your son most likely has your address listed as his place of residence on his driver's license which is information your insurance company can access via your state's DMV.
If you provide proof that he has his own insurance, they can exclude him as a driver and he will not impact your rates. Good luck and if you have any other questions, don't hesitate to ask