They will never be notified. Even though they are your parents, it is a violation of your privacy to share the details of your tax return with them.

If you do not mark "someone else can claim me as a dependent," and they are still claiming you, they will be notified that your SSN has been used on another return and it will reject their tax return if they e-file. However, they will never know more than that. 

As long as you indicate they are claiming you, they will NEVER know anything.